On a few of my sites when using Requirements::CSS etc. when clicking between pages there's a very brief flash of white, before every page load, in every browser. This doesn't happen on every site using requirements.
My remedy to this is to not use Requirements or <% require %> and use <link>, a mild inconvenience and not ideal.
I notice Silverstripe puts a timestamp on the end of required file paths, what's the purpose of that? Could it be causing the issue? Because essentially the only difference between using the requirements and using <link> is this timestamp, and that required css are at the bottom of the <head> tag.
Again, this is happening across a few sites, no current examples as they are all live and using <link>.