How high should the wear level of laptop battery be before replacement?

I've used my laptop for 4.75 years and HWInfo says that the battery has been permanently depleted by 38.1%. The battery life has noticeably gotten worse for over a year now, and the performance when my laptop isn't plugged has deteriorated. Not just that, but in recent months for CPU bound games, I'll get random stutters that very noticeable although they only last for 1-3 seconds max. Updating drivers, lowering settings, verifying files, restarting OS, using performance mods, etc., either don't work or only temporarily. I do also suspect that my CPU's thermals have dried up, so I'll probably have to re-apply it.