[otrs] Compose hanging with big attachment

Hi all, using 2.4.7. Ticket comes in with a big .txt attachment. Takes a couple of seconds to open, hitting "empty answer"-compose option. All we get is "waiting for otrs..." at the bottom of the browser. it sometimes then opens about 5 minutes later, not always however. This has also happened when ticket contains a LOT of text. Is it doing some conversion from richtext to html? is there a way around this? thanks in advance Neil