Way better than any Office alternative but also extremely sluggish on my machine. I just use it to read csv files and even at that it's abnormally slow.
If it's specific CSV files that are causing an issue, and you don't mind sharing them, you could attach them to a bug report: https://bugs.documentfoundation.org
Also try resetting your profile in case that's an issue: https://wiki.documentfoundation.org/UserProfile#Resolving_co...
I'll do some more testing and report.