Toilet refill

My toilet cystern takes an age to refill once flushed - will replacing any of the parts make it go quicker or is it as it is for another reason.

Is the toilet fed from the mains or cold water tank in the loft.
The best way of telling is if you turn off the water at the main stoptap and flush the loo. If it keeps on refilling after a couple of flushes then you have a tank fed loo. If so you should check the valve seat in the ball valve is a low pressure one, the hole should be approx 6-8mm.
They are colour coded but I dont have one to hand to tell you.
Also the seat may have debris which can easily be removed.
If it is mains fed I would consider changing the whole inlet system including a part 3 float valve

don't forget the overflow must be able to take the full flow of water so if you end up with a toilet that fills in 10 seconds you may also have a flooded room if your valve fails - easy to test tho, just hold down the float and watch the overflow work.

One of my toilets takes longer to fill than the others (it's a newish house and you get more toilets than you can shake a stick at these days). It's the one I had problems with and had to replace the syphon. I've got a feeling that there is a restricting kit supplied with some of these in case you have too high water pressure. I'm beginning to wonder whether I fitted this inadvertantly when I put it in but I couldn't be bothered to dismantle the whole lot again as it all works and no one else in the family has noticed. (I hope they don't notice this either or else it'll be on the list of things to do next weekend!)

Ian, my parents' house had a slow-filling toilet. When the plumber took a look at it it turned out that a washer was incorrectly fitted and was restricting the water flow but without causing a leak. I can't remember which washer as it was 10 years ago. Anyway, that one WAS a problem because it took a good 5 minutes to fully refill.