I'm considering upgrading a Celeron M380 (self reported

you should probably consider upgrading to another system altogether
in fact, i'm pretty sure there are schools giving away their C2D systems out there

>>62348295
are you using it for vintage games?

I have a pentium M 755 laptop (nc8000) with 2 GB of RAM, and it's REALLY slow for today's workload. it didn't use to be. back in the days, it only had trouble playing 720p or higher H.264 video (100% CPU for 720p, and dropped frames for anything higher). everything else worked perfectly (in particular web surfing with regular browser).

recently I gave it another spin with XP (with all the POSReady updates up till august 2017). it can BARELY load web pages (even google). it's almost always at 100% with basic surfing. I won't digress about this being proof of how javascript ruined the web. however for functionality, it won't do much. You can run office 2003 on it, and maybe play light games (it has a mobility radeon 9600) without the CPU maxing out and the fans always spinning at max. in fact I think it'll work for almost anything save web surfing.
windows 7 is even worse. 100% CPU use nearly all the time (even just loading notepad...), and fans really loud. room also gets hot fast... similar results on linux mint mate 18.1 x86 live CD

tl;dr
single core processors prior to core2 are underpowered for today's uses. upgrade, or use for lightweight vintage games. not much more.