I've used UTime for the past several years and have never had anyone crash. The code is also not "crap and outdated" (although I agree some things like using UniqueID should be changed).
I HIGHLY doubt that UTime uses enough memory to cause a Lua panic error (error occurs when client runs out of memory) because, actually looking at the code, all variables are networked between client and server and the UI is just drawn on the screen.
If people are crashing with a Lua panic error, I'm confident that another add-on is the cause.