GPUs are made to execute a limited set of the same operations operation on on a huge amount of data in parallel. This is a totally different workload than your usual computer programs, that commonly have a long and complicated series of commands. Thus just translating your program 1:1 to your GPU computer would make it way slower. Your GPU runs probably around ~1.5GHz, a third of your CPUs. The GPU does have a few thousand cores that run in parallel while our consumer CPUs does have at best a dozen (that are more capable than any single GPU core), but most of those are often already idle, since it's a lot of work to make your software take advantage of them. For some tasks it's worth it, and those take advantage of e.g. you GPU.