Conclusion - Server Response Time
Server Response Time Comparison
Just switched from Managed Wordpress Hosting to cPanel Ultimate Hosting and thought to post a relative speed comparison between products using GTMetrix https://gtmetrix.com as the long term benchmark service speed monitor for the same website codebase (custom WordPress theme), used on a daily basis over a number of years.
cPanel + Sucuri Combo
Granted this is not truly apples-to-apples as I'm now using Sucuri's WAF + CDN front-ending of cPanel for security reasons. Sucuri offers a combined package deal included a CDN (Content Delivery Network) as well as a WAF (Web Access Firewall).
Managed WordPress Hosting
On the plus side of MWH their "varnish" based server side memcache regularly used to provide an average server response time around the 300-400ms mark without additional CDN service, as of this current date.
I was using Autoptimize https://wordpress.org/plugins/autoptimize/ to cache my WordPress pages that then were additionally cached by varnish memcache. The website code has not changed on cPanel, the same website is still using Autoptimize to minimize server side PHP calls to WordPress core.
cPanel Ultimate Hosting
Uncached v Cached Page Speed
cPanel Ultimate hosting tends to be a lot slower without a CDN, no surprise really. But an apparently poor server response time often around the 1s (second) mark.
With the Sucuri CDN (a separate service/purchase) then the server response time is around 180ms mark if you hit a cached version of the page, via the Sucuri CDN.
If you hit an uncached version of the page the server response time is 1s for the first page call. This maybe caused by a long time delay between Sucuri's proxy servers and GoDaddy's hosting servers, there's no way for me to tell for certain...
Except when you look at a different cPanel Economy Hosting account, that I don't have Sucuri's WAF & CDN setup on, just the vanilla hosting package.
cPanel Economy Hosting
A vanilla cPanel Economy Hosting account (on a separate server cluster to cPanel Ultimate Hosting) regularly gets a 300-400ms server response time, much better and more reasonable without any cache support. This is a different WordPress codebase but again uses Autoptimize with a Twenty Sixteen customized theme.
Overall Page Load Speed Comparison
There is an overall apparent website load speed increase of about 1s moving from Managed WordPress Hosting to cPanel Ultimate Hosting in combo with Sucuri's CDN on cached page calls but approximately the same page load time on uncached page calls.
Hope this helps anyone else comparing services.
Just to clarify and to be fair.
It is likely a vanilla cPanel Ultimate Hosting setup would give a much improved server response time, likely milliseconds, without the Sucuri proxy server call on an uncached page, based on the seeing the performance of cPanel Economy Hosting vanilla setup.
If anyone has cPanel Ultimate Hosting setup (vanilla, no Sucuri) and can verify server response times that would help confirm timing. Note that each hosting server cluster is likely going to be slightly different (to a degree) in response times.
Main Page URL
Looking a bit deeper at the waterfall analysis, I think it's the initial page call on the main website url www.yourwebsitehere.com address that has the larger time lag but not the main website images.
Images Similar Speeds
The main website images look like they are returned at a similar speed in both cases, so are likely still in the Securi CDN cache at the time of testing (?) Which makes it curious about the initial main page call, why is that not apparently served from cache as well?
Images Pulled into Cache Immediately After Main Page Call (both times)?
Alternatively once the main web page has been called the images are immediately pulled at that time and placed into cache immediately for Sucuri to serve, so there is no difference in image serve time (first or second).
Sucuri Caching Time
Securi says they cache pages for 180 minutes (3 hours) before dropping from their access points if no request has been made in the last 3 hours for the web page.
The screenshots below show the initial main website url page call being 1.1 seconds and then on immediate testing again via GTMetrix gives 104 milliseconds. The image server response times remain approximately the same in each case.
Uncached Initial Page Call (1.1s)
Cached Initial Page Call (104ms)
If the page is called a third time then the reduced 100ms speed is repeated/maintained so maybe just the direct url being called is dropped from Sucuri cache after 180 minutes but the images associated with the website in general remain in cache? The exact details I am not sure about.