Oh no way an i3 will do then. You need cores. A minimum of a 4-core i5, preferably an i7 with four physical cores and four more virtual cores. If you can afford the price boost of a K-series chip and overclock them a little, you will see further performance increases in coding (reduced compiling time).
Your choice will be dependent on your budget and availability. Right now the Skylake CPUs (i5 6600K and i7 6700K for example) are overpriced due to manufacturing shortages. I would not buy one right now. You can still find Haswell CPUs (i5 4690K and i7 4790K for example) for a decent price. The downside to buying those however is they are older tech and run the soon-to-be-outdated DDR3 memory.
The Skylake chips run on the new DDR4...