perf: un-Box frames

[DaniPopes]

I believe this change was made to reduce memory consumption, however the initial problem was a memory leak which was fixed. So I don't think this is necessary anymore, and it should slightly improve performance because of cache locality of the frames inside of the Vec, as well as removing an initial allocation when creating the frame.

[codspeed-hq]

CodSpeed Performance Report

Merging #2761 will not alter performance

_{Comparing DaniPopes:frame-unbox (f10d438) with main (549ca96)}

Summary

✅ 171 untouched benchmarks

[rakita]

Additionally, allocating multiple frames at once (as it is one vec) will be slightly faster when the frame is used for the first time.