>I have Visual Studio 2017. I just found out that when having too many files on the project, that the Solution Explorer is crawling. I have 551 files in the Classes and 371 in the root of the Web site. Before, I was scrolling smoothly across the Solution Explorer. Now, it takes like 15 seconds for each page down.
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>What can I do to accelerate that?

Can you post your VS 2017 version?

Also I suggest to install 'everything' (interesting name). It helps to search drive.