Like James said, water temp has virtually nothing to do with drilling Carbide.
It will suck if you're used to drilling Stainless.
Copper electrode, use single channel if possible.
If you have many holes to drill, don't settle for a "suggested" setting ( assuming you have a reasonable control over generator parameters)
For one-offs, I just set it to something and drool over how uselessly little I can drill with a full 16" electrode.
When it comes to production, I dick with the settings until .... Well, let's just say that have had a 250 piece 1" carbide ball drilling job, 2.7mm ( opened the hole on the wire later to .125 )
The first ball ate practically 2 trodes to go through.
After a 4-5 hour battle of playing with settings, I've ended up with a 10% electrode wear, giving me 15 balls/trode, at the cost of something like 8 minutes/hole.
Disclaimer: This is on a 75A generator machine, so I did have plenty power to put into it.