The CJT page still won't load for me so I've started doing some more detective work. I went into the database and removed 2 code blocks I'm not using. I'm down to 12 code blocks and the CJT page still doesn't load. Every single code block has less than 20 lines of code.
I exported everything from the wp_cjtoolbox_blocks table then deleted all blocks so I'd have 0 code blocks. The CJT page then loads in WordPress. When I click the New Code Block button nothing happens, except that an error is generated in the Chrome console:
Uncaught ReferenceError: tb_show is not defined in blocks-page.js:232
This prevents me from adding a new code block.
I then reimported all blocks, then deleted all but 1. The CJT page loads. After looking at the block, I think I know why it's timing out. The site that this is on has over 1,500 blog posts and 275 pages. This plugin lists all posts and pages for every single code block. For a large site, this requires a lot of resources! Maybe you could add an option to not print out blog posts by default. If the user wants to see all blog posts listed, they would go to a specific block, click show posts, then make an AJAX request to show them for that block only.
For now I've re-imported all my code blocks. As expected the CJT page stops loading.