Sounds like you've built a nice render farm box. Now it's time to build a sketchUp machine. Thankfully the SketchUp machine will be dirt cheap because you only need a few gigs of ram, a gaming videocard and a single processor or high speed multi-core processor. I would say this could be done with a few hundred dollars depending on what parts you have laying around. You could get an 1155 board on ebay for like 50, an i5 or i7 in the 3 ghz range that can be overclocked to 5 ghz for around 150-200 and an older GTX 4 or 5 series for around 100. now if you have a few parts laying around you're set to build with sketchup and do renderings on your other box while you work. I would imagine that this will be faster than any settings you can make on that box you're currently using.
However, I think you might be having an issue some where that can be resolved on your current system. Sketchup hasn't changed all that much over the years and you should be able to handle it with this setup.
I wonder if this issue happens with all dynamic components or just a certain set?
Yes, an SSD will be a noticeable increase in performance on the whole machine but specifically larger software packages like adobe and autocad. SketchUp will load much faster.