Debugging an ASP.NET website that is running slowly?

Question

We're getting more and more complaints from users that our ASP.NET 4.5.2 website is running slowly or just generally "freezing up." Things look fine from our test servers and from our workstations, but we're probably using better workstation hardware and browsers than our customers. We're running ASP.NET 4.5.2, C#, SQL Server.

What are some areas that we should concentrate on for debugging such a nebulous request? Should I be looking at system performance and resources on the application servers? System performance and resources on the SQL server? We're tracking application page load times, and they don't seem to be excessive or much changed from months ago, even though customer complaints have gone up.

What are some best practices for starting our investigation, and where's the low hanging fruit on improving performance overall?

Answer 1

If your page is getting slower "sometimes" during the day, I would suggest first to check the Performance Monitor at your IIS server. This could easily be an issue with the server hitting it's limits (Machine or IIS settings). One way verifying this is by creating a sandbox server and run your application from there for your testers.

After that if you are executing stored procedures, add a monitor function in them to gather some cases and then check if any of them causes the process to freeze or delay.

I must also mention here the possibility of locked tables, so maybe a code review maybe in line. (most time consuming from all the above..)

This should be able to give you a hint where your issue originate.

Good luck

Answer 2

If you suspect some SQL problems, you can try to run a Sql Server Profiler to check what is running at the moment and if there is something that could be "freezing up" your system. This way you can check what is going on when the system is slow.

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