I was going to use the title asking ‘why are people still deleting the cache?’ until my colleague Corrie came up with this much better one! Rather than asking why you are still doing it – I am telling you not to! I know there is a lot of history behind this one, and for those of you that used Project Server 2007 in its early days there were some challenges such as the ‘check-in pending’ saga that got people in to the habit of deleting the project cache. We fixed the problem, then we fixed it again (and again) and you should not generally be seeing any issues with leaving your cache alone to do its job. However, many customers I talk to are routinely deleting the project from the local cache before they open it and then again after they close it! Why!?! Its job is an important one – it saves you having to pull that data from the server again – which will reduce network traffic, the hit on both the web services and the database, which means they can be getting on and doing useful stuff. I’ll also address a miss-conception here that I have heard from a number of customers – the choice of where to load the project from – cache or server? You don’t have a choice – Project will load it from the cache if it is there, and then load any incremental pieces it needs from the server, to get you the current version of that plan. In the screen shot below: the line actually reads ‘Retrieve the list of all projects from Project Server’. It does not also read – ‘…and open any I might choose after clicking this link from the server and ignore the local cache’. You don’t get the choice and you don’t need to choose. I’m sure many of you will not have read this far before clicking the comments option to tell me of all the problems you are having.(and I’m sure some of you are still having problems). First check that you have the latest cumulative updates and service packs. If you are still really having issues unless you delete the local cached copy then we certainly need to hear about it so we can fix the problem rather than have you waste your time and system resources doing things that you should not need to do. I will admit that there can be times when as support engineers we will ask you to remove your local cache to troubleshoot specific scenarios. The cache itself also has intelligence that allows it to decide that it may have some bad stuff – and it will get a new clean copy of data from the server (symptom of this will be several files in the cache directory with 1,2,3 etc. at the end). There have also been a few bugs we have worked on recently which ONLY surface when the user has cleared their cache! So please, if you have been deleting your cache as a matter of routine, then either stop – or speak to your PMO or IT people and ask why they have you do this – and if we need to fix something else then we can take a look.