Did a quick benchmark with a Wine application (most affected by KPTI) on 4.9.75 and Cinebench under Wine used to be at 100% CPU utilization both at normal and very high process priorities with a non KPTI kernel. Now, at both priorities, some cores are given less work so CPU usage would only be around 85% on very high priority. You lose at most 100 Cinebench points on a 6 core hyperthreaded. Heavy multi-threaded workloads are seeming like the ones hit hard by this.
Needless to say, very bad news for the Wine community except on Ryzen. If anyone is crazy enough to run Photoshop CS6 on Wine, you may slow down on image previews by quite a bit.