This is particularly noticeable on small apps I am used to seeing open the moment I click them. The best way I Can describe it I suppose its kind of lag a heavy a/v lag, but it even does it if I disable real time checking in defender.

I still have my win8 on another boot device I can boot to on demand and here is some figures, I did these by recording and slowing down the playback to estimate a time, the time is based on the app window appearing. Rounded to nearest tenth second. Both are from SSD, I also tested from spindle on win8 and it was faster than ssd on win10. Other performance metrics seem ok, there just seems to be some odd overhead on starting up programs.

Also office 365 is super fast so its not applying to every executable, I think the pattern seems to be "older" programs.

Securecrt
Win 8 0.1 seconds
Win 10 1.9 seconds

Keeppass
Win 8 0.1 seconds
Win 10 0.7 seconds

- - - Updated - - -

So I watched task manager when starting and noticed a svchost went high in cpu every time I launched securecrt, checked the services tab and its the font cache service. Disabled it and now starts instantly, mystery solved.

Now off to see if disabling that service has any downsides.

Now also found this O_o Will disabling windows font cache service impact performance?