KPTI + Retpoline Linux Benchmarking On Older Clarksfield / Penryn ThinkPads
To some surprise, the GIMP performance was measurably impacted by KPTI + Retpoline support and the older T61/W510 laptops were impacted more than the X1. But in the context of these GIMP tests it's only a difference of a second or two, so not too noticeable for an end-user using this image manipulation program.
The Redis performance was more noticeably affected on the older pre-PCID laptops than with the Broadwell-powered ThinkPad X1 Carbon.