Not sure how smart it is to move from 1 "dead" socket (AM3+) to another "dead" socket (LGA 1150) -- both AMD's Zen line next year & Intel's Skylake line later this year will be using brand-new sockets that won't be compatible with their forerunners.
That being said, there's a chance that whatever issue you're having isn't necessarily tied strictly to your CPU. A GTX 750Ti, for example, is not exactly a high-end GPU -- currently Tom's Hardware gives it an "honorable mention" in the sub-$150 range, because it's the fastest card that (depending on the model) doesn't require its own PCIe power connectors, but it costs more than the R7 260X (which provides the same performance, & their $115 pick) & is only slightly cheaper than the R9 270 (their $150 pick, with better performance). And poor performance could also be affected by your RAM, a slower HDD, or any other factors.
So, first off, what are your complete specs: Motherboard, PSU (make, model & wattage), RAM (speed, # of sticks, & total), OS (including 32- or 64-bit), hard drive, etc.? Secondly, what are the particular issues you're having -- FPS drops, unable to load a game, etc. -- and what games/apps are they affecting? Finally, have you tried any troubleshooting to see if maybe there's a component issue (i.e. tracert or QoS speedtest to make sure your ping & Internet connection aren't causing lag spikes)?
Based on those answers, we can help you pinpoint where some issues might be, as well as suggest some potential short-term (i.e. for a year to 18 months) upgrades that would help with performance, while you wait & see how Skylake & Zen settle out.