Having a slow web page can have multiple causes. The following article will help determine more precisely why a specific page is loading slowly.
1. Gather Information
Is this happening on a specific page or is it happening on all pages and has it been duplicated on another computer, tablet or other device?
A. If this is happening on specific pages, are these pages sharing the same information, data, or widgets?
B. What theme and version of Spark Pay online stores is currently running on the store and is it heavily customized?
a. If it's a V1 theme, they are table based which is a slower way of providing data. A newer V2 or V3 theme will load the same data much quicker.
C. Is the website running slow in specific browsers?
D. Are there custom scripts running and if so what are they?
E. Did this recently start occurring and what were the changes made?
F. Is the site using tables to align content? This is an older method that isn't best practice as most themes and stores are more responsive on all devices.
The placement of the elements of the site should be handled by the CSS for faster load times.
G. Is the site slow occassionally or constant?
H. Does refreshing the page make it faster?
I. Is the admin panel/dashboard running slow?
a. If both the admin panel and website are slow, it is indicative of the server being at fault.
2. Running Tests
a. On gtmetrix.com, you can download a full .pdf report at the end of the test. It will give some suggestions on what can be changed to improve load time.
b. Summarize the information from these test.
3. Translating Results
A. On gtmetrix.com, in the waterfall view is there a long green line (time to first byte)?
B. In the waterfall view of the webpagetest.org result are there any sections with long blue lines (Content Download)?
a. If so, what is the content that is taking long to download?
i. If you are seeing multiple .jpg pictures, take a look at them. Are these photos or did someone create them in an image production software? If it is an
image and not a photo, it is suggested that they be converted to a .png format instead.
C. In the gtmetrix report, are there pictures that need to be resized?
a. This would be a minor issue in the page load speed, however if they have a lot of pictures this would be an issue.
D. Are there calls being made to external websites?
a. If so, what is being called from the other sites? If it is just an image, it is suggested that the picture be hosted on your store's server, so it downloads from there instead
of having to bypass connection with another location, causing a slow loading process.
E. What is the item that is taking the longest to load? How big is the file?
4. Further Testing
A. If you temporarily hide a widget one at a time and run the webpagetest.org:
a. Did this improve site load speed? If so, by how much?
B. Is the external content the last thing to load on the page?
a. If it loads too early, calling the external content before the page starts to render in the browser can be troublesome, especially if there is a delay in pulling the information.
You want these to load late in the process, so that the page beings rendering before it start downloading information from the other domains.