Intel does not have a released processor that is unaffected by meltdown. AMD claims that it is unaffected by meltdown.
However, benchmarks have been released by numerous sites and the real world implications of the software patch aren't really that concerning to the average user. For example, looking at the benchmarks from techspot they found that the performance decrease in games range from 0% to 4%, while some things like blender and excel were unaffected by it.
The big performance hit is if you do continuous writes at 512K and lower with an ssd which gives you up to a 40% performance hit, while reads slowed down by up to 17%.
If you are using your computer normally without expecting to heavily read and write files like hosting a database, then you won't notice a significant performance decrease. Even if you wait a little bit it will take time, perhaps over a year, before companies solve this problem on a hardware level and then tool machines to produce them. If you want to avoid the meltdown patch you can get an AMD processor and not patch your windows computer, however you should wait a bit to see if AMD's claims are true.