One client said I had 50 or 60. No lag.
Discussion
if you have fast internet and good hardware, might not be noticeable. i don't see a good reason to have that many relays though. if you want your notes to go everywhere, you can just add the blastr relay wss://nostr.mutinywallet.com
My Internet isn't fast (I download and watch later rather than attempt streaming), and my phone was free with my cell plan two years ago.
This accumulation of relays is from various clients. I wouldn't know which ones to remove, so fuck it. I don't notice problems from it and have a very modest setup.