Check the speed limits and acceleration limits in your firmware.
The default speeds in many of the firmwares are maximums for specific machines (most of the firmware people either own specific machines or are employed by specific manufacturers), and not a nice safe value that "just works" on the majority of them (and what's a majority of a bunch of home-built setups anyway?).
With less current, you can't quite step as fast, so you will "miss" steps regularly. Given it's close to (but not quite) 50%, I would suspect that the acceleration is fine but that the max speed is too fast, and you need to reduce it. I suspect this because as it tries to accelerate, there will be a period where it will step reliably before it gets to the speed that causes missed steps. That said, best to check both speed and acceleration.
Note: I would divide each value by 2 each time till it works reliably (only do one axis at a time). Once it works, slowly increase the value till it fails, then back off a bit.
The default speeds in many of the firmwares are maximums for specific machines (most of the firmware people either own specific machines or are employed by specific manufacturers), and not a nice safe value that "just works" on the majority of them (and what's a majority of a bunch of home-built setups anyway?).
With less current, you can't quite step as fast, so you will "miss" steps regularly. Given it's close to (but not quite) 50%, I would suspect that the acceleration is fine but that the max speed is too fast, and you need to reduce it. I suspect this because as it tries to accelerate, there will be a period where it will step reliably before it gets to the speed that causes missed steps. That said, best to check both speed and acceleration.
Note: I would divide each value by 2 each time till it works reliably (only do one axis at a time). Once it works, slowly increase the value till it fails, then back off a bit.