Hard to keep rpm's up in the heat

I was just wondering if its normal that when it's hot outside and my car has been sitting in a parking lot or something, when I push in the clutch to change gears the rpm's drop a lot faster than normal thus resulting in a jerky shift. Has anyone else noticed this and is it normal? Could it be that when it's hot I also tend to have the a/c on (I've been told this reduces engine power)??

Thanks

yup, when the AC is on, you notice a lot of things change. Throttle response and power are lost and boost vacuum is lowered. to like 18 pounds at idle (instead of 22) according to my gauge.

So it seems like RPMs dropping would also be a combination of all this.