diff --git a/crates/base-db/src/lib.rs b/crates/base-db/src/lib.rs
index 358ca1453d2..b65cf7341f3 100644
--- a/crates/base-db/src/lib.rs
+++ b/crates/base-db/src/lib.rs
@@ -53,7 +53,7 @@ pub struct FileRange {
     pub range: TextRange,
 }
 
-pub const DEFAULT_LRU_CAP: usize = 128;
+pub const DEFAULT_PARSE_LRU_CAP: usize = 128;
 
 pub trait FileLoader {
     /// Text of the file.
diff --git a/crates/hir-expand/src/ast_id_map.rs b/crates/hir-expand/src/ast_id_map.rs
index 2b27db0e950..e48caca790c 100644
--- a/crates/hir-expand/src/ast_id_map.rs
+++ b/crates/hir-expand/src/ast_id_map.rs
@@ -115,6 +115,7 @@ pub(crate) fn from_source(node: &SyntaxNode) -> AstIdMap {
                 }
             }
         }
+        res.arena.shrink_to_fit();
         res
     }
 
diff --git a/crates/ide-db/src/lib.rs b/crates/ide-db/src/lib.rs
index b9f9cbd7fba..b0c5820fb09 100644
--- a/crates/ide-db/src/lib.rs
+++ b/crates/ide-db/src/lib.rs
@@ -149,29 +149,33 @@ pub fn enable_proc_attr_macros(&mut self) {
     }
 
     pub fn update_parse_query_lru_capacity(&mut self, lru_capacity: Option<usize>) {
-        let lru_capacity = lru_capacity.unwrap_or(base_db::DEFAULT_LRU_CAP);
+        let lru_capacity = lru_capacity.unwrap_or(base_db::DEFAULT_PARSE_LRU_CAP);
         base_db::ParseQuery.in_db_mut(self).set_lru_capacity(lru_capacity);
-        hir::db::ParseMacroExpansionQuery.in_db_mut(self).set_lru_capacity(lru_capacity);
-        hir::db::MacroExpandQuery.in_db_mut(self).set_lru_capacity(lru_capacity);
+        // macro expansions are usually rather small, so we can afford to keep more of them alive
+        hir::db::ParseMacroExpansionQuery.in_db_mut(self).set_lru_capacity(4 * lru_capacity);
+        hir::db::MacroExpandQuery.in_db_mut(self).set_lru_capacity(4 * lru_capacity);
     }
 
     pub fn update_lru_capacities(&mut self, lru_capacities: &FxHashMap<Box<str>, usize>) {
         use hir::db as hir_db;
 
         base_db::ParseQuery.in_db_mut(self).set_lru_capacity(
-            lru_capacities.get(stringify!(ParseQuery)).copied().unwrap_or(base_db::DEFAULT_LRU_CAP),
+            lru_capacities
+                .get(stringify!(ParseQuery))
+                .copied()
+                .unwrap_or(base_db::DEFAULT_PARSE_LRU_CAP),
         );
         hir_db::ParseMacroExpansionQuery.in_db_mut(self).set_lru_capacity(
             lru_capacities
                 .get(stringify!(ParseMacroExpansionQuery))
                 .copied()
-                .unwrap_or(base_db::DEFAULT_LRU_CAP),
+                .unwrap_or(4 * base_db::DEFAULT_PARSE_LRU_CAP),
         );
         hir_db::MacroExpandQuery.in_db_mut(self).set_lru_capacity(
             lru_capacities
                 .get(stringify!(MacroExpandQuery))
                 .copied()
-                .unwrap_or(base_db::DEFAULT_LRU_CAP),
+                .unwrap_or(4 * base_db::DEFAULT_PARSE_LRU_CAP),
         );
 
         macro_rules! update_lru_capacity_per_query {