This was due to an oversight on my part, I was using a very slow way to get player information from our database to determine what shop discount you should have. I have now updated this code to work pretty much instantaneously (14ms now or 1% of the time it used to take!)
I've also sped up the way the online web based shop works and it too now makes purchases instantly. This is quite a minor change (literally 1.4 seconds has been saved per purchase

I know for some of our power buyers these little delays really get on your nerves so I'm happy to have had the time today to correct this problem.