If it's just the chat and/or activity feed you need from the dashboard, you can add those popouts to your OBS window as custom docks (chat supports BTTV and/or FFZ there)
Will recommend against using SLOBS, but if you want to test, you can import scenes/settings between both versions.
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Additionally, there's GPU acceleration you can enable/disable in Chrome somewhere, if not Firefox, see if that changes anything, if using the twitch dashboard popout as OBS docks doesn't get the job done instead.