If you are looking to perform the same analysis on multiple small files and wish to accumulate the results, the quickest way to do this would be to append them into a single LabChart file.
This can be achieved by opening the first file to be analysed, then choosing File>append... and picking the next file you wish to add. Continue in the same way until you have opened as many files as you wish to analyse.
Please be aware that creating very large data files will considerably slow the time to analyse the file. This will also depend on your computer processing power, operating system and any other programs that may be running.