I tried to find anything that looks like a bottleneck on a system similar to yours, with the default theme, lots of posts, images and even comments.
Profiling showed a max difference of about 0.5 seconds for the plugin being active or not on the front-end.
Before we dive deeper into your system, analyzing your other plugins etc., we can try some patching to exclude CWX Project from the front-end completely.
I hope you’re able to edit PHP files … You can edit the following locally and then upload it, or edit directly on the server …
Open ‘plugins/cwx-project/cwx-project.php’ in an editor and go to line 186 insert a new line and enter the following on the new line (187)
if(!is_admin()) return;
The result should look like so:
// register_uninstall_hook(__FILE__, array('self', 'uninstall'));
if(!is_admin()) return; // <- new code you inserted
add_action('plugins_loaded', array($this, 'updateCheck'));
Save the changes and see what happens after activating the plugin.
Please let me know if this fixes your issue or not.