Is yours fitting loosely? Mine is a bit tight and I always cum in it quickly.

I use Astroglide in mine, and spritz a shot or drop
of water every few minutes. It stays slick for me that way.
Some lubes could ruin the rubber with repeated use
over a period of time.

For you uncut guys:
I'm uncut also... my Fleshlight feels nice when
I slide my cock in all the way to my balls.
But when I pull back out it's usually my foreskin
rolling over my cock like a "sleeve" as I pull out.
I presume the same thing happens with a real vagina
( I never had a real vag before. lol. Don't laugh! )
So, I don't see any problem there.

Fleshlight too tight?
Try loosening the end cap to let some air out
as you fuck your fleshlight.
Of course you might lose some suction that way,
but you'll get a good slide going in and
pulling back out.
I leave the cap off on mine so that I can slowly
edge my cock in and out of it.

Some guys love their fleshlights Tight
with full suction, so they'll screw the end cap
all the way shut.

I use the basic lube you can get on amazon. cheap and really effective!

I use ID Glide, which is readily available.

I don't tend to use much and just add a few extra drops or a bit of saliva/water every now and again to keep things moving.

I just ordered a pocket pussy and I hope to use it soon. My preferred lube is baby oil. Stays wet and slippery longer and yup.