Jayce Gives Lag

I've seen some board posts from 3 years ago saying playing with a jayce or playing against him, when he Clicks R it gives them lag spikes. I had a jayce on my team today, he was top lane, I was bot, but every time he switched his abilities from mercury to his (shooting gun?) he'd give me a heavy fps drop. I've asked other people about it in the past and some of them say YES Jayce is the only champion to give them a complete freeze (sometimes he'd give me a freeze) in their game. Some people tell me to get a new computer. BUT, no one else gives me drops but Sion after he dies and then stops his passive. I think it may be a graphics issue, but I'm curious to know if this is a bug with his ultimate. It might just be me. I'd still like to report it, and if you'd like to move it to help, then that'd be fine too.