Improve efficiency of CSV reader
ParaView's CSV reader is not particularly efficient for large files. See issue #18180 (closed) for discussion.
While CSV is not a particularly good format for large data, they are simple to generate and (for better or worse) are fairly common. A couple ideas might be to assume all values are numeric, or to allow the user to specify the format string. An additional thought would be to have a GUI to help the user determine how they'd like the data to be imported, akin to Matlab's file importer (see image below).