There is a large (about 1 second) delay when opening tabs. I noticed it when I already had around 25 tabs open in this window. The thing is, my computer isn't even close to hitting a resource cap. I have plenty of ram, cpu, disk etc. available, but the delay is still huge. It doesn't happen in safari.
I would include a video, but it's hard to show a delay
Version 1.0.0 (139), WebKit 623.1.8.0.0
Tahoe (26)