The main problem with native ajax endpoint is that it had to load whole WordPress core. Unless something is causing those slowdowns in your code it's likely something else bogs down that process.

Going through a different endpoint will no help you in this case since you still need to load core and back to square one.

Couple of seconds doesn't sound normal and I would recommend to first figure out where does that delay comes from.

The only practical technique for fast ajax endpoint in WP is custom core load with SHORTINIT, but that is limited to private projects since it cannot be practically coded generic enough to distribute in public solution (though some do and that crap breaks on any install slightly less than dead default).

The main problem with native ajax endpoint is that it has to load whole WordPress core. Unless something is causing those slowdowns in your code it's likely something else bogs down that process.

Going through a different endpoint will no help you in this case since you still need to load core and back to square one.

Couple of seconds doesn't sound normal and I would recommend to first figure out where does that delay comes from.

The only practical technique for fast ajax endpoint in WP is custom core load with SHORTINIT, but that is limited to private projects since it cannot be practically coded generic enough to distribute in public solution (though some do and that crap breaks on any install slightly less than dead default).