Do a cold boot, and check how full your drives are getting.  Try clearing all caches, web browser histories, everything you can that is hogging disk space and memory.  Settings/Apps and other tools in Windows can clean a lot of crud off.  I use CCleaner Pro, which works pretty well at freeing up memory, cleaning up a dirty Registry, putting unused apps to sleep, identifying apps that need to be updated or are just plain unused, etc.  All that gunks up your PC and slows down Zemax.  Check how many virus protection codes are running.  McAfee, Norton and MalwareBytes all compete for memory and clock cycles and run their own virus protection, which annihilates Zemax runtimes.  It's a pain, but re-install your Zemax, as it’s never been good at doing its own housekeeping and molds like week-old bread if you don’t.  Look in the directory where you’re storing your in-work lens.  Often there’s a ****_HAMMER.zmx file there which might have your latest file in it.  Use Global rather than Hammer once in a while just to get those GLOPT files on disk, which have your latest versions in them.