My Right-to-left site uses clean Bootstrap subtheme and has CDN, Internal caching (including Boost), Minification, Compression and aggregation, but still I get very low grades with all that has to do with CSS performance. Therefore I tried to inline all the CSS in my site via AdvAgg (please see image), what helped me in another theme, but not this time...
Is there anything else you think I should try?
What you are trying to do with the CSS inlining can only happen when the CSS is coming from Drupal, internal resource. External CSS resources cannot be inlined. If you read at the top of the "Inline CSS/JS On Specific Pages" it says, "This will prevent all local CSS and/or JavaScript files...". I agree that it is somewhat subtle and might need to be highlighted better in the UI that it only works for internal resources.Here is a screenshot of what I am referring to.
The only option you have with external CSS resources with AdvAgg is to move them to the TOP of the page. You could move the resource to the bottom of the page via a hook_alter_css in a custom module. But seeing this is the bootstrap CSS I can guarantee that will render your website broken.
Unfortunately, you cannot do anything about the CSS file with Pagespeed. You could host the CSS file in your site, but then you would lose the advantage of the CDN, which I see that the rest of your site is not using a CDN. Remember that Google Pagespeed scores are only one of many benchmarks and tests you should use in making a website perform. It is best to compare many different sources of data for optimizing your site (Pagespeed, YSlow, Pingdom Page Test, Webpagetest.org, etc.) And with optimization you have to give and take, it is nearly impossible to get a perfect score because you have to make sacrifices in certain areas. Being this CSS file is on a CDN and it is minified already, the impact to your site is honestly low. If you were to move the CSS to your site so AdvAgg could inline it, it would actually be worse for your site. It is a large CSS file that is critical for rendering your website, a CDN is the best place for it! I personally have found Pagespeed to be unrealistic in it's scoring from time to time.
Your setting for Inline CSS on specific pages is wrong. The path you should set is:
node/*
node/*.
node part? If so, then you're right, the path should be */node. If not, and your paths are the regular (e.g.) www.beniaharon.co.il/node/1, it should be node/*. RTL doesn't come into it, unless you've somehow managed to convince Drupal to serve its node pages from an unusual path as part of your RTL conversion
Inlined CSS is a double edged-sword...
It makes the page load quicker for the first visit to a site as there are no additional http requests to load the styles. However, for subsequent visits it is actually detrimental since with non-inlined css they would then be served up from the browser cache and cause pretty much zero load delay, whereas the inlined CSS adds to the page weight and thus load time of each and every page loaded.
It can be a useful tool to prevent an HTTP request by adding a few lines of CSS to a page but I certainly wouldn't recommend it for inlining hundred or thousands of lines of CSS, unless of course you are expecting the majority of visitors to visit only one page.
I'd say a good aggregation strategy is preferable to prevent large number of CSS files from being loaded on that first page load.
