I took the unit apart, drilled a 3/8" hole in the front panel plastic directly in front of the remote control infrared photodiode sensor and put the unit back together. Now the remote control is snappy. My guess is the plastic used in the Insignia filters infrared. You'll need a phillips screwdriver, a drill, and about 4 drill bits going from small to 3/8", a dust spray can to blow away the plastic shavings and about 30 minutes to accomplish this mod.
I'm sure this voids your warranty, and causes sudden loss of life, etc, etc.
When I took the unit apart, the sensor looked to be a standard TSOP381 photodiode, but the plastic look thick, dark, and had a grid in front of it (WTF?). Drill it out and get back relaxing on the couch instead of reading AVSForum...
My remote setup is a iPhone Redeye. The Redeye Insignia codes don't work so you need to capture all the keys from the remote which adds another 30 minutes