The site I am currently maintening was developed by another developer but it is very very slow. It takes about 12- 15 seconds for the home page to load and around 5-12 seconds for any other page. I have installed numerous plugins but nothing. I have reduced every image and yet nothing.
One out of the many problems that arise is the first byte time at 4-5 seconds. It also has too many http requests (150 - 180).
Problem is that I have no access to the server whatsoever since it is into another person’s authority. I can only access its cpanel and nothing else. According to his “tests”, the server does not overload at any point. But, he does have his reasons for saying that (that’s another issue alltogether).
How can I check the type of hosting? Do you mean server characteristics (cpu, ram, etc.?)
It seems that - as @andydavies pointed out - you need to fix the TTFB. Broadly speaking, this is the amount of time that is required for the server to accumulate all of the content required to build the html framework of the page ( as opposed to the downloadable resources like images, fonts, css etc ).
As this may require database access and server side processing, this is stuff that can only be addressed by the server configuration and sizing ( in relation to the load ). There is nothing that you can do about this apart from installing some kind of cache ( W3TC always used to be a good one but they seem to have lost their path a bit ), so that the page doesn’t need to be built from scratch very often.
Once that has been done, the next thing to do is looking at combining some of the files ( css and js are a good start ) to get the resource count down from 190 to an acceptable number - IIRC W3TC will do that for you too. ( note if you do have http2 available - unlikely! - then this becomes less of a performance problem )
"Optimize the performance of your website by tweaking the way Apache handles requests.
Compress Content
Apache 2.0 and 2.2 allow you to compress content before sending it to the visitor’s browser. The types of content to be compressed are specified by MIME type. This feature requires Apache’s mod_deflate to function correctly.
Disabled
Compress All Content
Compress the specified MIME types."
Should I select the “Compress All Content”? Will it make a difference?
Not to the TTFB no. You don’t want to compress all content, as image formats are about as compressed as already possible. You do want to ensure all content that is text-based is compressed though - you can often get a 10 times shrinkage in size.
However, as I said, it will not affect the ttfb ( except potentially to slow it slightly ).