system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does the same website sometimes load lighting fast with just 1-2MB of download speed and other times struggle to load up all the way with 10MB+?

To clarify...where I live I have 1-4MB depending on the day but often it works just fine, with every website popping up immediately. So it surprises me when I am overseas at a hotel or cafe with 10-20MB of speed that the internet can often lag a bit. I can tell a big difference when streaming but not browsing. Perhaps it's related to the number of people logged into to the same WiFi network...actually, I am sure that's it now that I think about it but I'll ask anyhow.
gpt
Your browser caches pages and will save it to your device to speed loading. That cache will periodically get cleared and require the entire site to be loaded again. Ads add a lot of overhead as well with images, animations, video etc. If those change it will impact loading time. Plus there are a lot of libraries that may need to get loaded behind the scenes. Again, ads may call different libraries that also need to be loaded. Then there's the time of day you visit. There may be higher traffic at certain times of day. There might be issues with a server somewhere along the line. There are tons of issues that can come up that will slow things down but ads are mostly to blame.