Your profile says you have a 2009 model and you say the other slides don't seem to operate as fast as they used to. Though I'm not experienced with the hydraulic slides I have read that the hoses used are not all that high quality. My experience with hydraulic systems leads me to suggest you examine the hoses for any bulging, cracking, dampness (seepage) or swelling. Beware, when checking for bulging, dampness or swelling it's best to wear leather gloves. If the hose has steel wire braiding sticking out of the hose it will be sharp and can penetrate quite deep, rubber gloves will not stop it. Seepage can happen for quite some time before you need to add oil to the tank.
Some hoses will delaminate as they age. I have seen the inner liner of hoses split and the oil gets between the layers, the pressure will then force the inner layer to restrict the hose. Sometimes the inner layer will break into chunks and get pushed to smaller places of the system like fittings and plug them. This can happen because of age and is always the first sign of hose failure. Even high quality hoses can experience this type of failure.
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, seasonal since 2000
Car Shredder Op/Tech, Scrap Metal Recycling - retired
The Faster I Go, The Behinder I Get.