diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index b8bc435e23..bdfc660624 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -1019,9 +1019,10 @@ pub mut:
 	imports               []Import // all the imports
 	auto_imports          []string // imports that were implicitly added
 	used_imports          []string
-	implied_imports       []string          // ​imports that the user's code uses but omitted to import explicitly, used by `vfmt`
-	embedded_files        []EmbeddedFile    // list of files to embed in the binary
-	imported_symbols      map[string]string // used for `import {symbol}`, it maps symbol => module.symbol
+	implied_imports       []string                  // ​imports that the user's code uses but omitted to import explicitly, used by `vfmt`
+	embedded_files        []EmbeddedFile            // list of files to embed in the binary
+	imported_symbols      map[string]string         // used for `import {symbol}`, it maps symbol => module.symbol
+	imported_symbols_trie token.KeywordsMatcherTrie // constructed from imported_symbols, to accelerate presense checks
 	imported_symbols_used map[string]bool
 	errors                []errors.Error   // all the checker errors in the file
 	warnings              []errors.Warning // all the checker warnings in the file
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 3fccd9661b..34b2cb8fc2 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -4261,7 +4261,7 @@ fn (mut c Checker) ident(mut node ast.Ident) ast.Type {
 		}
 		mut name := node.name
 		// check for imported symbol
-		if name in c.file.imported_symbols {
+		if c.file.imported_symbols_trie.matches(name) {
 			name = c.file.imported_symbols[name]
 		}
 		// prepend mod to look for fn call or const
diff --git a/vlib/v/parser/enum.v b/vlib/v/parser/enum.v
index f6d0ed8468..5ce4120ee1 100644
--- a/vlib/v/parser/enum.v
+++ b/vlib/v/parser/enum.v
@@ -61,7 +61,7 @@ fn (mut p Parser) enum_decl() ast.EnumDecl {
 			end_pos)
 		return ast.EnumDecl{}
 	}
-	if enum_name in p.imported_symbols {
+	if p.is_imported_symbol(enum_name) {
 		p.error_with_pos('cannot register enum `${enum_name}`, this type was already imported',
 			end_pos)
 		return ast.EnumDecl{}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index a62901e096..46be078400 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -89,7 +89,7 @@ fn (mut p Parser) call_expr(language ast.Language, mod string) ast.CallExpr {
 		}
 		or_kind = if is_not { .propagate_result } else { .propagate_option }
 	}
-	if fn_name in p.imported_symbols {
+	if p.is_imported_symbol(fn_name) {
 		check := !p.imported_symbols_used[fn_name]
 		fn_name = p.imported_symbols[fn_name]
 		if check {
@@ -152,7 +152,7 @@ fn (mut p Parser) call_args() []ast.CallArg {
 		} else {
 			expr = p.expr(0)
 			if mut expr is ast.Ident {
-				if expr.name in p.imported_symbols && !p.imported_symbols_used[expr.name] {
+				if p.is_imported_symbol(expr.name) && !p.imported_symbols_used[expr.name] {
 					// func call arg is another function call
 					// import term { bright_cyan, colorize } ... colorize(bright_cyan, 'hello')
 					p.register_used_import_for_symbol_name(p.imported_symbols[expr.name])
@@ -393,7 +393,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			}
 		}
 		if !p.pref.is_fmt {
-			if name in p.imported_symbols {
+			if p.is_imported_symbol(name) {
 				p.error_with_pos('cannot redefine imported function `${name}`', name_pos)
 				return ast.FnDecl{
 					scope: unsafe { nil }
diff --git a/vlib/v/parser/module.v b/vlib/v/parser/module.v
index 8e8d8bd5fd..a9eb511694 100644
--- a/vlib/v/parser/module.v
+++ b/vlib/v/parser/module.v
@@ -36,7 +36,7 @@ fn (mut p Parser) register_used_import(alias string) {
 fn (mut p Parser) register_used_import_for_symbol_name(sym_name string) {
 	short_import_name := sym_name.all_before_last('.').all_after_last('.')
 	short_symbol_name := sym_name.all_after_last('.')
-	if short_symbol_name in p.imported_symbols {
+	if p.is_imported_symbol(short_symbol_name) {
 		p.imported_symbols_used[short_symbol_name] = true
 	}
 	for alias, mod in p.imports {
@@ -322,12 +322,13 @@ fn (mut p Parser) import_syms(mut parent ast.Import) {
 	for p.tok.kind == .name {
 		pos := p.tok.pos()
 		alias := p.check_name()
-		if alias in p.imported_symbols {
+		if p.is_imported_symbol(alias) {
 			p.error_with_pos('cannot register symbol `${alias}`, it was already imported',
 				pos)
 			return
 		}
 		p.imported_symbols[alias] = parent.mod + '.' + alias
+		p.rebuild_imported_symbols_matcher(alias)
 		// so we can work with this in fmt+checker
 		parent.syms << ast.ImportSymbol{
 			pos:  pos
@@ -347,3 +348,12 @@ fn (mut p Parser) import_syms(mut parent ast.Import) {
 	}
 	p.next()
 }
+
+fn (mut p Parser) rebuild_imported_symbols_matcher(name string) {
+	p.imported_symbols_trie = token.new_keywords_matcher_from_array_trie(p.imported_symbols.keys())
+}
+
+@[inline]
+fn (mut p Parser) is_imported_symbol(name string) bool {
+	return p.imported_symbols_trie.matches(name)
+}
diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
index 613b12155d..3e025b609e 100644
--- a/vlib/v/parser/parse_type.v
+++ b/vlib/v/parser/parse_type.v
@@ -636,7 +636,7 @@ fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot b
 	} else if p.expr_mod != '' && !p.inside_generic_params {
 		// p.expr_mod is from the struct and not from the generic parameter
 		name = p.expr_mod + '.' + name
-	} else if name in p.imported_symbols {
+	} else if p.is_imported_symbol(name) {
 		check := !p.imported_symbols_used[name]
 		name = p.imported_symbols[name]
 		if check {
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index e3e12dc099..f22ff8cc37 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -86,6 +86,7 @@ mut:
 	implied_imports          []string // ​imports that the user's code uses but omitted to import explicitly, used by `vfmt`
 	imported_symbols         map[string]string
 	imported_symbols_used    map[string]bool
+	imported_symbols_trie    token.KeywordsMatcherTrie
 	is_amp                   bool // for generating the right code for `&Foo{}`
 	returns                  bool
 	is_stmt_ident            bool // true while the beginning of a statement is an ident/selector
@@ -343,6 +344,7 @@ pub fn (mut p Parser) parse() &ast.File {
 		mod:                   module_decl
 		imports:               p.ast_imports
 		imported_symbols:      p.imported_symbols
+		imported_symbols_trie: token.new_keywords_matcher_from_array_trie(p.imported_symbols.keys())
 		imported_symbols_used: p.imported_symbols_used
 		auto_imports:          p.auto_imports
 		used_imports:          p.used_imports
@@ -592,8 +594,7 @@ fn (mut p Parser) check_name() string {
 	name := p.tok.lit
 	if p.tok.kind != .name && p.peek_tok.kind == .dot && name in p.imports {
 		p.register_used_import(name)
-	} else if p.tok.kind == .name && p.peek_tok.kind == .dot && name in p.imported_symbols
-		&& !p.imported_symbols_used[name] {
+	} else if p.tok.kind == .name && p.is_imported_symbol(name) && !p.imported_symbols_used[name] {
 		// symbols like Enum.field_name
 		p.register_used_import_for_symbol_name(p.imported_symbols[name])
 	}
@@ -2698,7 +2699,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 			return ast.FnTypeDecl{}
 		}
 	}
-	if name in p.imported_symbols {
+	if p.is_imported_symbol(name) {
 		p.error_with_pos('cannot register alias `${name}`, this type was already imported',
 			end_pos)
 		return ast.AliasTypeDecl{}
diff --git a/vlib/v/parser/struct.v b/vlib/v/parser/struct.v
index a5c7d69f3b..df1cee88ba 100644
--- a/vlib/v/parser/struct.v
+++ b/vlib/v/parser/struct.v
@@ -73,7 +73,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 		p.error_with_pos('struct names must have more than one character', name_pos)
 		return ast.StructDecl{}
 	}
-	if name in p.imported_symbols {
+	if p.is_imported_symbol(name) {
 		p.error_with_pos('cannot register struct `${name}`, this type was already imported',
 			name_pos)
 		return ast.StructDecl{}
@@ -651,7 +651,7 @@ fn (mut p Parser) interface_decl() ast.InterfaceDecl {
 	mut pre_comments := p.eat_comments()
 	p.check(.lcbr)
 	pre_comments << p.eat_comments()
-	if modless_name in p.imported_symbols {
+	if p.is_imported_symbol(modless_name) {
 		p.error_with_pos('cannot register interface `${interface_name}`, this type was already imported',
 			name_pos)
 		return ast.InterfaceDecl{}
diff --git a/vlib/v/token/keywords_matcher_trie.v b/vlib/v/token/keywords_matcher_trie.v
index 2f0ed5953e..34efb8b7f6 100644
--- a/vlib/v/token/keywords_matcher_trie.v
+++ b/vlib/v/token/keywords_matcher_trie.v
@@ -11,6 +11,11 @@ pub mut:
 	max_len int
 }
 
+// str returns a short representation of matcher
+pub fn (km &KeywordsMatcherTrie) str() string {
+	return 'KeywordsMatcherTrie{ /* nodes.len: ${km.nodes.len} */ min_len: ${km.min_len}, max_len: ${km.max_len} }'
+}
+
 // TrieNode is a single node from a trie, used by KeywordsMatcherTrie
 pub struct TrieNode {
 pub mut:
@@ -18,6 +23,14 @@ pub mut:
 	value    int = -1 // when != -1, it is a leaf node representing a match
 }
 
+// str returns a string representation of the node content
+pub fn (node &TrieNode) str() string {
+	if isnil(node) {
+		return '&TrieNode(nil)'
+	}
+	return '&TrieNode{value: ${node.value}}'
+}
+
 // find tries to find the given `word` in the set of all previously added words
 // to the KeywordsMatcherTrie instance. It returns -1 if the word was NOT found
 // there at all. If the word was found, find will return the `value` (value => 0),