Increasing the amount of RAM on a desktop or laptop will not improve the FPS you have without a better RAM. RAM will only affect the system performance and stop the stuttering you have.
Read this thread to help you.
http

/www.neowin.net/forum/topic/1091311-in-what-way-does-adding-extra-ram-help-pc-gaming-performance/
Some games will require more RAM than others. Like how Battlefield requires more than Minecraft. I would like to quote this in.
Phew...that was a lot of benchmarking! Two systems, ten different games, three memory amounts, and lots of runs of each benchmark. And what can we conclude? Well, it seems that the initial findings based on our first test system hold true - RAM amount simply doesn't make a big difference for performance - we witnessed at most a 4 percent difference in average frames per second jumping from 4GB to 8GB, and no boost to average FPS jumping to 16GB. Furthermore, part of the 4GB systems' deficits could have been due to running in single-channel mode. Based on our findings, we're confident saying that if you're on a tight budget, whatever money you spend on more than 4GB would definitely be better spent on the next level of video card, or perhaps a quad-core instead of a dual-core processor.
But there is a caveat, and it's a big one - you really have to "manage" your RAM more with 4GB. First of all, you'll want to limit background tasks. All of our tests were performed with the minimum of applications running in the background - if you tend to have a number of programs running while gaming, having just 4GB may be an issue. Also, keep in mind that you need to allow Windows to run a substantial page file when you have 4GB - our attempts to benchmark with the slim 1GB page file we use with 16GB of RAM led to running out of virtual memory upon launching some of our games with only 4GB of physical RAM.
So what's our advice? 8GB is probably the safest bet, not because it adds much to performance, but because it will allow you to do more with your system. As for 16GB - we'll stick to our guns here. We might run it in our test rig, but in no way, shape, or form do we recommend it to users who are only interested in maximizing gaming performance. The extra $60-70 is much better spent on other components. Maybe one day, if memory drops back down to $4/GB, which it hit in December 2012, we'll say "RAM is cheap, get 16GB," but until then, 8GB is our target for any reasonably-priced gaming system.
http

/www.techbuyersguru.com/Ramgaming2.php