The obvious answer is "throw a CDN and edge servers at it." But the real answer is: it depends on what's actually causing the 500 ms.
Is it network latency? Then yes, deploying closer to your users helps. Is it a difference in traffic volume? Then it's a scaling problem, not a geography problem. Could even be the underlying network infrastructure in the region, which you have little control over.
The first step is always to identify what's actually causing the issue before jumping to a fix.