I have this effect also sometimes, but not always. It’s also different from client to client. With Thunder on Android it’s most of the time really fast. On the other hand I’m using sometimes Voyager, where it’s a mix between slow and fast. I use the website only in rare case’s. But when I do, it was always fast.
Darktable? It’s a RAW developer and photo managing software on Linux, Windows and Mac, a little bit like Adobe Lightroom, but OpenSource. If GPS coordinates are in the RAW, sidecar or jpg files, the photos can be displayed in the map module. Much better, if you have a GPX file and no GPS data embedded, you can assign the photos to the GPX route, as long the timestamp of DateTimeOriginal in Exif is accurate. If the timestamp differs, you can specify the difference.
Maybe Digikam can do the same. But I don’t like the KDE framework which is used there. Digikam is available for Linux and Windows (yes, I know it’s strange).
Maybe you can try to switch your browser to the so called “porn mode” or “private window” and login there. This will decouple your current session and you don’t have to clear the cache. If the community is also visible here, send a mail to the admin and ask for help. He is a nice guy.