Does opening browser developer tools affect application performance?

Question

I would like to know if opening browser developer tools really affect the application performance in any way. It's not about just considering opening the developer tools in the same window, it can be in a new window or the same window.

Also is there any difference in application rendering/performance if developer tool is not opened vs opened state?

Answer 1

Opening the developer tools definitely affects performance, and not always in the way you might expect.

In Chrome I very frequently find opening developer tools whilst a page is running slowly, can improve the page's performance. I don't know why that is, but it's a very observable affect.

It will probably be worth instrumenting your page within your own code and logging general performance stats if you're worried about developer tool's influence. You can open the developer tools and read the log after triggering whatever you're measuring.