Unfortunately you’re not missing something – we don’t have out-of-the-box support for cumulative calculations. That said, this is something that could be easily added to a custom chart plugin. I haven’t checked our existing plugins to see if any of them support cumulative graphs or not, yet – I’d recommend checking them out, and if none of them support it, you could consider sponsoring one of them to add it if you really need the feature.
Generally, group by operations done on top of search will be done on the server in a single request, so it should be pretty fast. If there are more than 100 groups in the result, we load them 100 at a time, so a chart that tries to display 1000 data points at once might be a little slow.
If you do a group by on top of a list that doesn’t come straight from a search, depending on what operations you do to build the list, we may have to do the grouping in the web browser, which means loading all the underlying data to the web browser, which is much slower. So if you do a search -> advanced filter -> group by, that will take about as long as it would to load every result in the original search. Generally if we’re able to calculate the underlying list on the server, though, we’re also able to do the group by on the server.
(Sometimes Bubble will choose to do the grouping the web browser even if we don’t have to, if you’ve already loaded most of the results and we think it will be faster to just load all of them than it will be to do a separate group by search).