fix(tvix/eval): allocate Thunk::upvalues with known capacity r/4682

The capacity (i.e. number of builtins) is known from the lambda, so we
can size it correctly right away.

Change-Id: Iab0b5a3f47d450fa9866c091ebbbed935b934907
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6351
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/tvix/eval/src/value/thunk.rs b/tvix/eval/src/value/thunk.rs
index 3b7cb7f5f7..9d52ded3c4 100644
--- a/tvix/eval/src/value/thunk.rs
+++ b/tvix/eval/src/value/thunk.rs
@@ -51,8 +51,8 @@ pub struct Thunk(Rc<RefCell<ThunkRepr>>);
 impl Thunk {
     pub fn new(lambda: Rc<Lambda>) -> Self {
         Thunk(Rc::new(RefCell::new(ThunkRepr::Suspended {
+            upvalues: Vec::with_capacity(lambda.upvalue_count),
             lambda,
-            upvalues: vec![],
         })))
     }
 }