Hello there!

Here's a brief rundown of our current predicament:

We've had an eCommerce platform within our organization for a while now. It was initially compact, accommodating between 500 to 1000 product listings. The landscape changed around half a year ago, when we started aggressively adding more products. An impending need for expanded hosting facilities raised its head and we recently shifted to a different hosting service. Theoretically, this should have conferred an uptick in performance, however, the website has become incredibly sluggish. Has anyone else encountered this issue? There's a possibility the migration wasn't executed correctly.

We're using the OpenCart system.

The slowdown of your eCommerce platform after migration can be attributed to several potential factors. Here are a few things for you to consider:

Hosting Service: Your new hosting service might be providing insufficient resources or poorly optimized solutions for an eCommerce platform like OpenCart. You need to consider the server speed, location, and architecture of your hosting service. Resources like processing power (CPU), RAM, and storage (SSDs are faster than HDDs) play a critical role in the efficiency of your website.

Migration Execution: During your migration, data might have been incorrectly or inefficiently integrated. This could be leading to bad queries or data structure problems that result in sluggish performance. You might need to review the migration process and confirm its accuracy.

Database Indexing: OpenCart and other eCommerce solutions rely heavily on a database. If your database is not properly indexed, this can slow down your query executions, causing a bottle-neck situation for your database requests.

Coding Issues: Poor or out-of-date coding practices can greatly affect website performance, especially with platform transitions or product number increase.

Image/Content Optimization: If you've added a large number of products, it's possible that images or other content are not optimized, leading to slower load times.

Caching and CDN: Implement or improve caching solutions on your website to speed up load times. Utilize a Content Delivery Network (CDN) to quickly deliver content to users around the world.

Traffic: With the increase in products, if there's been a significant increase in traffic that exceeds your host's limitations, that could also be a reason for the slowdown.

Unoptimized Scripts and Plug-ins: Just like with poor coding practices, unoptimized or unnecessary scripts and plug-ins can cumbersomely load and impact negatively on your site's performance.

SEO and Redirect Chains: SEO and redirect chains can affect your site performance if not properly optimized. Unnecessarily long chains can place extra load time on the page, decreasing the overall speed.

HTTP/S Requests: Reducing the number of HTTP/S requests on your site can improve its speed. Each component on a site (images, scripts, CSS files) requires a different HTTP request, so reducing the number of elements can help.

Page Size: The more content (especially visuals like images and videos) contained in your pages, the larger their size, and thus, the longer they'll take to download and display.

Database Clean up: With increased products & user activities, your database can get cluttered. Periodic database optimization can help in maintaining the performance.

Server Configuration: Configuration of the server (php.ini settings, SQL server settings, etc.) can have a dramatic effect on your website's performance.

Web Application Firewalls: Misconfiguration or overuse of these security systems can sometimes slow down your website.

SSL/TSL Handshakes: Mismanaged SSL/TSL handshakes and encryption could slow down the loading speed of your website.

Complications With Foreign Keys, Joins, and Relationships: In eCommerce platforms, data is naturally highly relational and can be complex. If there are issues with how the data has been migrated and these relationships are set up, then this can cause performance problems.

Time-To-First-Byte (TTFB): It's worth checking there are no significant delays server side or with network connections that could increase the TTFB (the time it takes for a user's browser to start receiving information after it has requested it from the server).

Version of the Ecommerce Platform, PHP, or MySQL: You need to ensure that you're using versions of your platform, PHP, and MySQL that are fully supported and optimized. Older versions might not take full advantage of the latest speed and efficiency optimizations.

Implement HTTP/2: If you haven't already, implementing HTTP/2 can make a significant difference to site performance. HTTP/2 allows for increased parallelism in the way the browser makes requests to the server, meaning multiple requests can be handled at the same time.

API Calls: If your platform is making external API calls, these can be a potential source of delay. This applies to APIs for payment gateways, shipping cost calculators, third-party inventory systems, or any external resources that your website needs to interact with.

Check Extensions and Third-Party Modules: They should be compatible with your OpenCart version and should not slow down the system. If any of the modules/extensions are interfering with the system, it could result in performance issues.

Profiling Tools: Finally, you might want to use a profiling tool specific for PHP applications (like Tideways or Blackfire) to help identify any issues in your code or database queries. These tools can give you an in-depth view of how your system performs and may help identify the underlying issue.

In your case, as you've recently migrated to a new hosting service, you may want to consider looking closely at the configuration of the new hosting environment. Check-ups with your hosting service provider or a consultation with an expert could help you better diagnose the problem. You may also want to utilize website performance tools such as Google's PageSpeed Insights, Pingdom, or GTmetrix to get a better sense of your site performance and areas of improvement.

Take a look at the opencart debugger tool which provides insights into the number and duration of requests executed during page load.

We encountered issues related to high database load on the server. By implementing profiling techniques, we were able to identify and eliminate resource-intensive queries, resulting in a significant decrease in loads and the elimination of delays.
Loading times for a single page used to take 5-7 seconds prior to optimization.

In addition to requests, modifications were made to the settings or code, although I cannot recall the specifics at the moment. It is likely that a non-default theme, a large number of products, and incorrect settings played a part in the performance issues.

When you switched, did you switch hosts or did you also increase your capacity?
Perhaps it would be wise to consider getting a basic Virtual Dedicated Server (VDS).
Aside from the hosting issues, it might be worth checking your memory usage. Maybe everything is filled to the maximum with backups or unnecessary files.