Accuracy?

Will lead build-up in your cylinder ports on a revolver have any effect on your shooting?

Yup !! Need to keep the crud ring down else it will swage your bullets undersize before they leave the cylinder.

Yes, lead build up anywhere will affect the accuracy, whether its in the cylinder or in the barrel, if you're getting much of that, then maybe the rounds you are using are a little too hot for the soft lead projectiles, if you shoot hard cast lead you usually don't have much of an issue , unless you really load em hot.

I've been shooting a Super Blackhawk in .44 mag. 7.5" barrel since 1980. I've shot every type bullet there is and leading has never been a problem. Mainly because I don't allow it to build up because I clean frequently and target the cylinder ports and barrel.
Same thing with my stainless single six shooting pure lead bullets.
Years ago I cast bullets for .357 and .38 special and never had problems there either due to frequent cleaning.
There's no good reason to put off cleaning your weapon. I clean while sitting in my mancave while watching TV. I have a cardboard box I put on a folding chair in front of me lined with paper sacks and clean mostly with the pistol down in the box, no fluids get out and it's easy to clean up.
When I get started I often clean several pistols while I'm at it.
The more lead you allow to build up the more aggressive you must be in cleaning so I keep it simple and don't let it go that far.