tracker1

What are your resolution/quality settings... should probably set the resolution to 720p, and the quality to medium/high.  If you're trying something like 1080p or 1440p it will run slower.  Also, video cards under 4gb will not be able to do high detail in some games as the textures will be too big in memory.  As to Win10, if you're running 3rd party antivirus, unload it and go back to built in windows defender, or at least disable it while gaming.  Disable all the telemetry options, and also disable any 3rd party apps.  While 8GB of ram should be plenty, it's easy for background applications you don't really need to get installed and sit there taking up space.
 
The 750k isn't actually that great... unfortunately you're in for cpu + mb + ram when you are ready to upgrade.
https://cpu.userbenchmark.com/Compare/AMD-Ryzen-5-2400G-vs-AMD-Athlon-II-X4-750K/m433194vs1548

I wouldn't suggest lower than a Ryzen 2400g, generally speaking... you are probably CPU bottlenecked, see above on suggested quality settings.  If you keep an eye out on ebay, you may be able to get a 4000+ i5 or i7 relatively cheap, possibly with a motherboard, and ddr3 memory that you can upgrade to.  The userbenchmark site I referenced isn't the whole story, but does give you a good comparison baseline.

If you aren't using an SSD, you'll be amazed at the difference in upgrading to one for your primary drive.  That would be my second upgrade from where you are, if you aren't already using one for your main drive(s).
 
Third would be to bring the RAM up above 16GB, it's actually going to be more useful in browsing than gaming as if you have many tabs open, resource usage can build up relatively quickly.
 
Fourth would be the Video Card... I'd hold on to what you have with is a decent low-mid range card.  The landscape will probably change a lot in the next year here.
 
In any case, what you have should work well enough.  And you don't need to break the bank, just be a bit frugal and discerning in an upgrade strategy over time. You don't have to do it all at once either.  Also, you're often better going a generation or two back for the top of the line, used than current low-mid options.    My current system is nearly 6yo, thinking of upgrading early-mid next year, last upgrades about 2yr ago.