Two weeks ago a GPS performance update hit for the European editions of the HTC One M8, and today it's out for those with unlocked or developer edition phones. The update, which weighs in around 40MB (your exact mileage may vary) brings the software version to 2.22.1540.4 and is available now over-the-air.
It's a fairly simple changelog this time around:
This update contains important enhancements and bug fixes, include: - GPS performance improvement
So go ahead and fire up Settings > About Phone and check for an update yourself.