As someone with a bit fewer tabs (50-60) on similar hardware, the app does feel sluggish sometimes. I specifically notice it when returing to a session. It seems like Orion is restoring the state of too many tabs at once, or loading them too late when switching tabs. Sometimes a device reboot helps, other times it doesn't.
I don't know if there are steps to reproduce this issue, but something related to loading/reloading tabs may be the issue.