This has been going on for a while for me, and has recently gotten quite bad. There is a delay between me pressing my potion button/pet auto-potting and the potion taking effect on my HP/MP. It has caused me to die numerous times as I'm a Sniper and can only take 2 hits before dying at Himes, and its really frustrating losing 10% over and over when you're 9x. Is there anything I can do to mend this?
It is simply your connection to the server, and I am sure it is an issue you will find on any other server. It could be due to a number of factors including but not limited to, your connection speed, current server load, and physical distance between you and the server. So in short, I cannot think of anything you can do to remedy the situation besides adjusting your pot timing to compensate for lag.