Recently I just switched from 4.19 to 4.22.3 for myVR game project and observed the significant performance drop after. In my observation I found that with “Instanced Stereo” option enabled, the shader instruction count will increase 100+ in 4.22.3, just wondering if there are any issues with 4.22.3.
Its better not to switch engine versions for projects. There’re always issues with version changes.
Which platform are you targeting? I had the same issue with my Go project after upgrading to 4.22 and I couldn’t figure it out. However after upgrading again to 4.23 the problem was gone and I’m happily using 4.23 
Perhaps the same for your project?