I can't in all honesty throw a recommendation for anything Intel that's 8 threads or less for even mediocre gaming. The way games are expanding thread counts to incorporate the data they used to push on single threads at high speeds, lack of threads in your current processor is what's killing you. The Pentium is decent, especially for office/light computing, but for games its well down, if not below, any recommended and most minimum standards.
For low budget builds/upgrades, Amd is value king, by a landslide. Might not get the most fps (by a rather small margin) but minimum fps is considerably higher in anything cpu taxing. Which includes all the AI online games invariably use. A 3300x or 2600 would be the goto cpus.