Monitoring and optimizing the performance of a web application?

Question

Search Engine Optimization

Hello.
I want to discuss the possibilities for quickly organizing web site performance monitoring. The situation is as follows: There is a web site, attendance is about 11,000 people. per day, about 360,000 page views per day. The site is written in asp.net web forms + asp.net mvc3. Uses SQL Server 2012, hosted on a dedicated server. The problem is in the load on the processors, on the other subsystems (memory, disk, network) the load is acceptable.
Server: HP DL160 G6, 2 Xeon 5620, 32 GB RAM, 2 SAS HDD 15000RPM.
During peak hours, the processor load averages 90%, the rest of the time - from 15 to 60%.
You can solve the problem by installing more powerful processors, you can by optimizing the program code. When writing code, development time was more valued than performance, therefore, there are opportunities for optimization. The big question is where?
Actually a question for the community: how to monitor the site in order to determine which pages (which page parameters) cause the most CPU load. moreover, it would be desirable to carry out such monitoring at minimal cost. What will be the ideas?

Answer 1

newrelic.com ? ) Will help to find bottlenecks.
They will also give you a free t-shirt if you have time :)

Answer 2

Such a load 2 Xeon should not even notice at all. I have 50k and 300-400k hits on one Dual Core, although it is no longer enough in peaks, but that's a completely different story.
The advice here is standard - profiling the base, code, watch what loads the server and the CPU, and dance from this.

Answer 3

My iron is 2 times weaker and the disks are not sas. Holds 200k. Load in peaks, and then not strong.
From experience I confirm what was written above. Profiling requests, logging slow requests, see the load on disks ...