I don't want to come off as patronizing since you didn't ask for advice or anything. Hope it helps you, or someone else though.

Haha yeah, I'm still surprised at how far I've been able to push my limits.
Bit of a late reply, but that's where one of my old personal records was prior to leaderboards being introduced.

It's difficult, but the journey is super rewarding if you manage to push through.
For my old record I pushed from the 30s to 50s by relying on enemies infighting, and focusing entirely on survivability via dashspam + reflect melee spam. (although I play a completely different style now to push past 60+)
Unfortunately the same problem has been plaguing Cybergrind "high rounds" since the start; performance. Disabling gore (Disclaimer: I don't actually do this even though I probably should) greatly minimizes the frequency and impact of the FPS drops. This doesn't fix all of the problems, but it definitely helps.

Either adapting or practicing your own strategy in conjunction with better performance, then I think you'll be able to push your record.

WHAT!!! I'm on wave 35 at my best.