Several things here,
Run hwinfo in sensor mode to keep an eye on memory allocation when gaming. Make sure you dont have something simple like overheating.
As already said you absolutely should get a proper 16GB memory kit installed with good XMP profiles that matches your motherboards QVL. It will give you a nice performance bump. Ryzen loves higher speed RAM and dual channel is a must have.
Update the BIOS on Ryzen systems as there are regular fixes to issues that can come up.
Update drivers, with game updates you should update your video drivers as these also come with performance updates and you can imagine that memory allocation changes can be included in these.
This is probably the best advice on here. As always start with the lowest cost options first.
Update all your driver's, BIOS and check your BIOS profiles. Sometimes things get screwed up and optimised defaults can make a big difference.
If you don't have XMP/DOCP enabled do that, to at least as fast as your RAM is rated for. There is no points n having fast RAM without XMP/DOCP enabled.
Once you have done all that then look at upgrading RAM. Take a look at the price of the kits though. Play around with different options. 16GB is nice to have but not entirely essential. Having a second channel is a very good thing although not quite as important on Ryzen 2XXX as Ryzen 1XXX
Above all: make one change at a time and then test, with a variety of tests. MSI afterburner is very handy for frame rate testing.
One you are happy then stop for a bit and make sure you stay happy.