diff --git a/cmd/tools/modules/vgit/vgit.v b/cmd/tools/modules/vgit/vgit.v
index 766c3ced2c..efa2e8ab0d 100644
--- a/cmd/tools/modules/vgit/vgit.v
+++ b/cmd/tools/modules/vgit/vgit.v
@@ -102,6 +102,7 @@ pub mut:
 	vexename       string // v or v.exe
 	vexepath       string // the full absolute path to the prepared v/v.exe
 	vvlocation     string // v.v or compiler/ or cmd/v, depending on v version
+	make_fresh_tcc bool   // whether to do 'make fresh_tcc' before compiling an old V.
 }
 
 pub fn (mut vgit_context VGitContext) compile_oldv_if_needed() {
@@ -141,6 +142,9 @@ pub fn (mut vgit_context VGitContext) compile_oldv_if_needed() {
 	}
 	// Recompilation is needed. Just to be sure, clean up everything first.
 	scripting.run('git clean -xf')
+	if vgit_context.make_fresh_tcc {
+		scripting.run('make fresh_tcc')
+	}
 	scripting.run(command_for_building_v_from_c_source)
 	build_cmd := command_for_selfbuilding.replace('{SOURCE}', vgit_context.vvlocation)
 	scripting.run(build_cmd)
diff --git a/cmd/tools/oldv.v b/cmd/tools/oldv.v
index 3d7b03e1ac..399d93679b 100644
--- a/cmd/tools/oldv.v
+++ b/cmd/tools/oldv.v
@@ -39,6 +39,7 @@ mut:
 	cc            string = 'cc' // the C compiler to use for bootstrapping.
 	cleanup       bool   // should the tool run a cleanup first
 	use_cache     bool   // use local cached copies for --vrepo and --vcrepo in
+	fresh_tcc     bool   // do use `make fresh_tcc`
 }
 
 fn (mut c Context) compile_oldv_if_needed() {
@@ -50,6 +51,7 @@ fn (mut c Context) compile_oldv_if_needed() {
 		commit_v: c.commit_v
 		path_v: c.path_v
 		path_vc: c.path_vc
+		make_fresh_tcc: c.fresh_tcc
 	}
 	c.vgcontext.compile_oldv_if_needed()
 	c.commit_v_hash = c.vgcontext.commit_v__hash
@@ -125,6 +127,7 @@ fn main() {
 	}
 	////
 	context.cleanup = fp.bool('clean', 0, false, 'Clean before running (slower).')
+	context.fresh_tcc = fp.bool('fresh_tcc', 0, true, 'Do `make fresh_tcc` when preparing a V compiler.')
 	context.cmd_to_run = fp.string('command', `c`, '', 'Command to run in the old V repo.\n')
 	commits := vgit.add_common_tool_options(mut context.vgo, mut fp)
 	if should_sync {
diff --git a/examples/web_crawler/web_crawler.v b/examples/web_crawler/web_crawler.v
index 122aed5d9e..e32de54a57 100644
--- a/examples/web_crawler/web_crawler.v
+++ b/examples/web_crawler/web_crawler.v
@@ -2,13 +2,6 @@ import net.http
 import net.html
 
 fn main() {
-	/*
-	user_agent = 'v.http'
-    resp := http.get('https://tuicool.com') or {
-        println('failed to fetch data from the server')
-        return
-    }
-	*/
 	// http.fetch() sends an HTTP request to the URL with the given method and configurations.
 	config := http.FetchConfig{
 		user_agent: 'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0'
diff --git a/vlib/net/html/parser.v b/vlib/net/html/parser.v
index ac6e97e5d4..b9ad2a1266 100644
--- a/vlib/net/html/parser.v
+++ b/vlib/net/html/parser.v
@@ -13,11 +13,11 @@ mut:
 	is_attribute     bool
 	opened_code_type string
 	line_count       int
-	lexeme_builder   strings.Builder = strings.Builder{}
+	lexeme_builder   strings.Builder = strings.new_builder(100)
 	code_tags        map[string]bool = map{
-	'script': true
-	'style':  true
-}
+		'script': true
+		'style':  true
+	}
 }
 
 // Parser is responsible for reading the HTML strings and converting them into a `DocumentObjectModel`.
diff --git a/vlib/strings/builder.v b/vlib/strings/builder.v
index a406b0a223..855319f645 100644
--- a/vlib/strings/builder.v
+++ b/vlib/strings/builder.v
@@ -7,76 +7,59 @@ module strings
 // dynamically growing buffer, then use the resulting large string. Using
 // a string builder is much better for performance/memory usage than doing
 // constantly string concatenation.
-pub struct Builder {
-pub mut:
-	buf          []byte
-	len          int
-	initial_size int = 1
-}
+pub type Builder = []byte
 
 // new_builder returns a new string builder, with an initial capacity of `initial_size`
 pub fn new_builder(initial_size int) Builder {
-	return Builder{
-		// buf: make(0, initial_size)
-		buf: []byte{cap: initial_size}
-		len: 0
-		initial_size: initial_size
-	}
-}
-
-// write_bytes appends `bytes` to the accumulated buffer
-[deprecated: 'use Builder.write_ptr() instead']
-[deprecated_after: '2021-04-18']
-[unsafe]
-pub fn (mut b Builder) write_bytes(bytes &byte, len int) {
-	unsafe { b.write_ptr(bytes, len) }
+	return Builder([]byte{cap: initial_size})
 }
 
 // write_ptr writes `len` bytes provided byteptr to the accumulated buffer
 [unsafe]
 pub fn (mut b Builder) write_ptr(ptr &byte, len int) {
-	unsafe { b.buf.push_many(ptr, len) }
-	b.len += len
+	unsafe { b.push_many(ptr, len) }
 }
 
 // write_b appends a single `data` byte to the accumulated buffer
 pub fn (mut b Builder) write_b(data byte) {
-	b.buf << data
-	b.len++
+	b << data
 }
 
 // write implements the Writer interface
 pub fn (mut b Builder) write(data []byte) ?int {
-	b.buf << data
-	b.len += data.len
+	b << data
 	return data.len
 }
 
+[inline]
+pub fn (b &Builder) byte_at(n int) byte {
+	return unsafe { (&[]byte(b))[n] }
+}
+
 // write appends the string `s` to the buffer
 [inline]
 pub fn (mut b Builder) write_string(s string) {
 	if s == '' {
 		return
 	}
-	unsafe { b.buf.push_many(s.str, s.len) }
+	unsafe { b.push_many(s.str, s.len) }
 	// for c in s {
 	// b.buf << c
 	// }
 	// b.buf << []byte(s)  // TODO
-	b.len += s.len
 }
 
 // go_back discards the last `n` bytes from the buffer
 pub fn (mut b Builder) go_back(n int) {
-	b.buf.trim(b.buf.len - n)
-	b.len -= n
+	b.trim(b.len - n)
 }
 
 // cut_last cuts the last `n` bytes from the buffer and returns them
 pub fn (mut b Builder) cut_last(n int) string {
-	res := b.buf[b.len - n..].bytestr()
-	b.buf.trim(b.buf.len - n)
-	b.len -= n
+	cut_pos := b.len - n
+	x := unsafe { (&[]byte(b))[cut_pos..] }
+	res := x.bytestr()
+	b.trim(cut_pos)
 	return res
 }
 
@@ -87,14 +70,13 @@ pub fn (mut b Builder) cut_to(pos int) string {
 	if pos > b.len {
 		return ''
 	}
-	return b.cut_last(b.buf.len - pos)
+	return b.cut_last(b.len - pos)
 }
 
 // go_back_to resets the buffer to the given position `pos`
 // NB: pos should be < than the existing buffer length.
 pub fn (mut b Builder) go_back_to(pos int) {
-	b.buf.trim(pos)
-	b.len = pos
+	b.trim(pos)
 }
 
 // writeln appends the string `s`, and then a newline character.
@@ -103,10 +85,9 @@ pub fn (mut b Builder) writeln(s string) {
 	// for c in s {
 	// b.buf << c
 	// }
-	unsafe { b.buf.push_many(s.str, s.len) }
+	unsafe { b.push_many(s.str, s.len) }
 	// b.buf << []byte(s)  // TODO
-	b.buf << byte(`\n`)
-	b.len += s.len + 1
+	b << byte(`\n`)
 }
 
 // buf == 'hello world'
@@ -115,7 +96,8 @@ pub fn (b &Builder) last_n(n int) string {
 	if n > b.len {
 		return ''
 	}
-	return b.buf[b.len - n..].bytestr()
+	x := unsafe { (&[]byte(b))[b.len - n..] }
+	return x.bytestr()
 }
 
 // buf == 'hello world'
@@ -124,7 +106,8 @@ pub fn (b &Builder) after(n int) string {
 	if n >= b.len {
 		return ''
 	}
-	return b.buf[n..].bytestr()
+	x := unsafe { (&[]byte(b))[n..] }
+	return x.bytestr()
 }
 
 // str returns a copy of all of the accumulated buffer content.
@@ -135,17 +118,15 @@ pub fn (b &Builder) after(n int) string {
 // accumulated data that was in the string builder, before the
 // .str() call.
 pub fn (mut b Builder) str() string {
-	b.buf << byte(0)
-	bcopy := unsafe { &byte(memdup(b.buf.data, b.buf.len)) }
-	s := unsafe { bcopy.vstring_with_len(b.len) }
-	b.len = 0
-	b.buf.trim(0)
+	b << byte(0)
+	bcopy := unsafe { &byte(memdup(b.data, b.len)) }
+	s := unsafe { bcopy.vstring_with_len(b.len - 1) }
+	b.trim(0)
 	return s
 }
 
 // free - manually free the contents of the buffer
 [unsafe]
 pub fn (mut b Builder) free() {
-	unsafe { free(b.buf.data) }
-	b.len = 0
+	unsafe { free(b.data) }
 }
diff --git a/vlib/strings/builder_test.v b/vlib/strings/builder_test.v
index 15b5f2ebd0..a714722e45 100644
--- a/vlib/strings/builder_test.v
+++ b/vlib/strings/builder_test.v
@@ -3,7 +3,7 @@ import strings
 type MyInt = int
 
 fn test_sb() {
-	mut sb := strings.Builder{}
+	mut sb := strings.new_builder(100)
 	sb.write_string('hi')
 	sb.write_string('!')
 	sb.write_string('hello')
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 678283d53e..b8e6937dff 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -766,10 +766,11 @@ pub fn (mut c Checker) struct_init(mut struct_init ast.StructInit) ast.Type {
 					c.error('unknown struct: $type_sym.name', struct_init.pos)
 					return ast.void_type
 				}
-				if sym.kind != .struct_ {
+				if sym.kind == .struct_ {
+					info = sym.info as ast.Struct
+				} else {
 					c.error('alias type name: $sym.name is not struct type', struct_init.pos)
 				}
-				info = sym.info as ast.Struct
 			} else {
 				info = type_sym.info as ast.Struct
 			}
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 4a02131103..45c5757dff 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -126,7 +126,7 @@ pub fn (mut f Fmt) wrap_long_line(penalty_idx int, add_indent bool) bool {
 	if penalty_idx > 0 && f.line_len <= fmt.max_len[penalty_idx] {
 		return false
 	}
-	if f.out.buf[f.out.buf.len - 1] == ` ` {
+	if f.out[f.out.len - 1] == ` ` {
 		f.out.go_back(1)
 	}
 	f.write('\n')
@@ -149,7 +149,7 @@ pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) {
 	mut buffer := if cfg.imports_buffer { unsafe { &f.out_imports } } else { unsafe { &f.out } }
 	mut i := 0
 	for i = buffer.len - 1; i >= 0; i-- {
-		if !buffer.buf[i].is_space() { // != `\n` {
+		if !buffer.byte_at(i).is_space() { // != `\n` {
 			break
 		}
 	}
diff --git a/vlib/v/fmt/struct.v b/vlib/v/fmt/struct.v
index 6d9d014d6d..79eb18aa15 100644
--- a/vlib/v/fmt/struct.v
+++ b/vlib/v/fmt/struct.v
@@ -306,7 +306,7 @@ pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 		fields_start := f.out.len
 		fields_loop: for {
 			if !single_line_fields {
-				if use_short_args && f.out.buf[f.out.buf.len - 1] == ` ` {
+				if use_short_args && f.out[f.out.len - 1] == ` ` {
 					//           v Remove space at tail of line
 					// f(a, b, c, \n
 					//     f1: 0\n
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 19fd5f3c12..30ac14e712 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -5837,9 +5837,9 @@ fn (mut g Gen) insert_before_stmt(s string) {
 }
 
 fn (mut g Gen) write_expr_to_string(expr ast.Expr) string {
-	pos := g.out.buf.len
+	pos := g.out.len
 	g.expr(expr)
-	return g.out.cut_last(g.out.buf.len - pos)
+	return g.out.cut_last(g.out.len - pos)
 }
 
 // fn (mut g Gen) start_tmp() {
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 8b3f824629..bc23670931 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -39,7 +39,7 @@ fn (mut g Gen) process_fn_decl(node ast.FnDecl) {
 	g.gen_attrs(node.attrs)
 	// g.tmp_count = 0 TODO
 	mut skip := false
-	pos := g.out.buf.len
+	pos := g.out.len
 	should_bundle_module := util.should_bundle_module(node.mod)
 	if g.pref.build_mode == .build_module {
 		// if node.name.contains('parse_text') {
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index b72427bec1..727e39e4ff 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -314,25 +314,25 @@ pub const (
 	keywords = build_keys()
 )
 
-pub fn key_to_token(key string) Kind {
-	return Kind(token.keywords[key])
-}
-
+[inline]
 pub fn is_key(key string) bool {
-	return int(key_to_token(key)) > 0
+	return int(token.keywords[key]) > 0
 }
 
+[inline]
 pub fn is_decl(t Kind) bool {
 	return t in [.key_enum, .key_interface, .key_fn, .key_struct, .key_type, .key_const, .key_pub,
 		.eof,
 	]
 }
 
+[inline]
 pub fn (t Kind) is_assign() bool {
 	return t in token.assign_tokens
 }
 
 // note: used for some code generation, so no quoting
+[inline]
 pub fn (t Kind) str() string {
 	return token.token_str[int(t)]
 }
@@ -434,34 +434,41 @@ const (
 )
 
 // precedence returns a tokens precedence if defined, otherwise lowest_prec
+[inline]
 pub fn (tok Token) precedence() int {
 	return int(token.precedences[tok.kind])
 }
 
 // is_scalar returns true if the token is a scalar
+[inline]
 pub fn (tok Token) is_scalar() bool {
 	return tok.kind in [.number, .string]
 }
 
 // is_unary returns true if the token can be in a unary expression
+[inline]
 pub fn (tok Token) is_unary() bool {
 	// `+` | `-` | `!` | `~` | `*` | `&` | `<-`
 	return tok.kind in [.plus, .minus, .not, .bit_not, .mul, .amp, .arrow]
 }
 
+[inline]
 pub fn (tok Kind) is_relational() bool {
 	// `<` | `<=` | `>` | `>=` | `==` | `!=`
 	return tok in [.lt, .le, .gt, .ge, .eq, .ne]
 }
 
+[inline]
 pub fn (k Kind) is_start_of_type() bool {
 	return k in [.name, .lpar, .amp, .lsbr, .question, .key_shared]
 }
 
+[inline]
 pub fn (kind Kind) is_prefix() bool {
 	return kind in [.minus, .amp, .mul, .not, .bit_not]
 }
 
+[inline]
 pub fn (kind Kind) is_infix() bool {
 	return kind in [.plus, .minus, .mod, .mul, .div, .eq, .ne, .gt, .lt, .key_in, .key_as, .ge,
 		.le, .logical_or, .xor, .not_in, .key_is, .not_is, .and, .dot, .pipe, .amp, .left_shift,
diff --git a/vlib/vweb/sse/sse.v b/vlib/vweb/sse/sse.v
index 76d7d7822c..986c61828c 100644
--- a/vlib/vweb/sse/sse.v
+++ b/vlib/vweb/sse/sse.v
@@ -53,7 +53,7 @@ pub fn (mut sse SSEConnection) start() ? {
 		start_sb.write_string('\r\n$k: $v')
 	}
 	start_sb.write_string('\r\n')
-	sse.conn.write(start_sb.buf) or { return error('could not start sse response') }
+	sse.conn.write(start_sb) or { return error('could not start sse response') }
 }
 
 // send_message sends a single message to the http client that listens for SSE.
@@ -73,5 +73,5 @@ pub fn (mut sse SSEConnection) send_message(message SSEMessage) ? {
 		sb.write_string('retry: $message.retry\n')
 	}
 	sb.write_string('\n')
-	sse.conn.write(sb.buf) ?
+	sse.conn.write(sb) ?
 }
diff --git a/vlib/x/ttf/ttf_test.v b/vlib/x/ttf/ttf_test.v
index 646aa1a17b..7a6f02001f 100644
--- a/vlib/x/ttf/ttf_test.v
+++ b/vlib/x/ttf/ttf_test.v
@@ -156,7 +156,7 @@ fn save_raw_data_as_array(buf_bin []byte, file_name string) {
 	for x in buf_bin {
 		buf.write_string('0x${x:02x},')
 	}
-	os.write_file_array(file_name, buf.buf) or { panic(err) }
+	os.write_file_array(file_name, buf) or { panic(err) }
 }
 
 fn test_main() {