Image size has always been a confusing issue with IPB. I would like a simplistic way of setting maximum image sizes per members group by file size. This combined with the ability for members to upload any size images and the images will be automatically reduced to the maximum limit. I know this is just about currently achievable but it is not straightforward to set up and the size reduction is rather random.
My view is don't underestimate the effect a slow server has on membership. I lost members through not upgrading my server quick enough as they got tired of waiting for pages to load or images to upload. It is not only IP board to consider, what other IP add ons are you using Ip Gallery or IP blog, how many hooks etc ?? All impact on performance.
I have 500,000 post and about 8500 members and I have to run on a dedicated server. Overkill some might say, but the reality is if you want to keep your forum alive in a competitive market then you need to ensure the basics such as a quick loading forum is essential, especially as broadband speeds get faster. I switched to two different managed VPS servers and neither could cope with the demand of my board. I would consider an upgrade sooner rather than later.
As mentioned if you are not that adept with managing a server, then a managed VPS is absolutely essential. That slightly extra monthly cost is worth its weight in gold and will make your life a lot more trouble free !
You are right this issue seems to have been sorted. Originally limiting pixel size worked in resizing in dimensions but I originally found this did not significantly reduce memory footprint. This is now not the case as reducing pixel size now also seems to vastly reduce memory size.