Now I mostly blame Entity Framework and only slightly WPF. Entity Framework is a discordant combination of being easy to use and while at the same time extremely difficult to master. On the one hand it's pleasantly easy to create the schema and start using the entities in code the very same day (and by the same token also easy to fall prey to lazy practice that apparently will do a number on your performance), while on the other hand, it's very difficult to reign in the effects of this ease-of-use and the results can get out of hand. We have had several teams analyze performance from different levels - from the overall architectural choices made early on and down to the details of how views are written, entities materialized, and so forth. We've certainly made quite a few improvements, but the biggest of these came not from improving the efficiency of the data layer, but simply by wrapping the data operations in asynchronous calls. WPF shares a portion of the blame here as well. The queries, while slow, typically don't account for more than half or three quarters of the time a user spends wishing he was at the dentist instead. No, the rest of the time is spent rendering huge data grids. Why am I letting WPF off the hook easily you ask? Well, the problem here is largely attributable to design choices, such as caving in when the customer asked for data grids that show hundreds of rows of data with an equal number of columns. Another portion of the blame can also be leveled at Telerik, which while providing beautiful and functional controls is at the same time another dirty pig in this mud bath the user has to slog through. Nevertheless, I still can't help but blame WPF for some of the performance problems when I can see scroll bars chug along and occasionally see the entire UI lock up for entire seconds. But I shouldn't be so hard on this application since it really has sped up a lot over the last year. It was entirely normal to have to wait upwards of 30 seconds for a single tab to open and display nothing more complex than a simple message inbox. I am aware that care is required in tweaking the display of grids, but that's exactly the problem in my opinion. The whole technology stack we're using is extremely simple to use and yet infuriatingly, devilishly difficult to tune and tweak.
When I say this app dwarfs iTunes and makes Visual Studio feel like Notepad, I'm not kidding folks. I also admit that the app deals with huge amounts of data due to its "enterprise" nature. There is verbose logging being done in triplicate to the hard drive, the database and a logging service, which in a manner of speaking could be considered necessary since each log records different variations of the same events for different audiences. No data is being deleted and even our sparse test data set has bloated the client database to over 9gb, though most of this is transactional logging (exporting the same data sans transactional data yields a file that only weighs 300mb). Myriad small things have crept into the design and architecture of the application to meet very specific and sometimes narrow minded business requirements that were assembled by different business units within the same client organization. These requirements are often impossible, costly or just painful to implement in light of oftentimes conflicting or even duplicate requirements that originated from different business units. Lastly, the rigid and literal interpretation of design documents by the testing teams combined with unrealistically short turnaround times required for bug fixes has resulted in many suboptimal solutions to problems that never existed. I'm going to skip over the half dozen or so integrations to third party systems that are at the best of times brittle and non-functional, but I hope I've drawn a clear picture of the problem.