Performance and stability improvements on all platforms.

TBR=v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com

Change-Id: I56e139fe0427b8d3524d62f34f19dc1b327c2050
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1624767
Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/7.6.256@{#1}
Cr-Branched-From: b05ab0af1005491a1fe62f9c064908ea014e6bc6-refs/heads/master@{#61736}