If you're using ASIO4ALL or something, lower the input latency.. try 512 or lower. If you're not using an asio driver, try using an asio driver.
Having said that... there's potential here, but the quantizing just kills it dead. It's unfortunate but you'll probably need to re-record the entire piece. There are some quite odd transitions as well, where it jumps from loud to quiet and it seems quite sudden... probably in part due to the quantizing, but also more reverb could be utilized to help smoothen out some of the edges here. There are some parts, like that arpeggio at the end, where the velocity seems too consistent through the notes... could use some further expressiveness in the performance. This could also be a problem with the sample, I'm not sure what you use, but a real piano doesn't maintain such a perfectly consistent tone between notes like that. Something to think about but maybe not a huge deal.
I think most of all, re-recording it without quantization and latency will be the first step, then adding some tasteful reverb.