Escort AC Problem

Hi All

Need some help, I have a 1998 Escort 1.6 Zetec, when I turn the AC on, the car becomes very sluggish when accelerating, if you then turn the AC off again the car is then fine.
I am going to get the AC system recharged as it is not as cold as it used to be but I don’t believe this is causing the performance fault.
Has anyone else had a similar problem / any suggestions on where to start looking

Don't turn the AC on. It's gonna lagg the system. Adding straign on the pulley system, and causing the motor to rev slower, it'sa 1.6, my 1.9 laggs bad. my sister's 1.6 toyota motor won't make it through the blue bidge mountains with the AC on....