<Trace> tag in web.config makes site run normal. Without it, it runs extremely slow

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web.config

IIS8

I have a very strange problem. I have a webapplication that runned very smoothly. Last week I moved the webapplication from a server with Windows 2012 en SQL Server 2016, to a new server with Windows 2019 and SQL Server 2019. The new server has more CPU's, more memory.

But when I open my site and try to save changes, it's unacceptably slow. It can take minutes to save. The problem is not the database, I've checked that. Running the same locally on my dev-PC, no problem.

Now I've added the following to my web.config to trace and try to figure out the problem. And that's the strange thing. With this it runs at normal speed.

<trace pageOutput="false" requestLimit="10" enabled="true" localOnly="true" traceMode="SortByTime" mostRecent="true"/>

How can this be? I don't want trace to be enabled for security reasons. But when I remove it, my webapp is slow again.

Anyone any answers?

What I have tried:

Made sure the cause of the problem wasn't the database. I compared the web.config with the old situation, where it was running fine, to see if there are any discrepencies, but there aren't. Apart for a rewrite that I removed, it's exactly the same. Adding the rewrite back didn't help either.