I was still seeing some slowdowns from time to time on this new server. My host just informed me that they only just finished moving over all of the VPS slices to the new server, so the slowdowns were likely I/O from all of the moves. But - they saw that we were using a good chunk of our allotted memory, so they bumped it up from a 400MB slice to a 1024MB slice at no extra charge.
I just had to quickly reboot the server for it to see the new memory size, so we were down for a minute or two, but all is well now.
I've been quite pleased with
rimuhosting overall, and would definitely recommend them to anyone looking for a helpful, responsive VPS hosting company.