Doesn't necessarily mean it will be faster renders, depends on settings L&P used, could just mean better quality renders but considering the quality of current renders, I lean towards it being faster renders now.
I don't know what render settings L&P use, certainly better than what I use on my own PC and suspect he might not use "Max Time" setting as I do, as his PC with the RTX Titan is MUCH faster than mine
So all in all, this could be a waste of my time posting this but, just an FYI for everyone in regards to any developer upgrading their system.
When a developer upgrades a card, it does mean they have "more time" available to them due to faster renders. However, they could use that time to increase the quality of the render rather than faster render times.
Like for example, when I upgrade PC in future, I would most likely still have the same render time but the quality of renders would increase. Most developers is going to have a balance between "time to do" and "quality of renders" and that very much depends on the PC they currently have.
I would imagine a 3090 graphic card would lessen the need to do that though, so it should mean faster renders and therefore quicker updates in regards to L&P, but I wouldn't presume so.