I exchanged a few messages with one of my clients, each a few lines long. The first message they sent me had an attachment but the rest of them didn't.

After a few messages where exchanged, the quoted messages got longer and longer. To make a long story short, after about seven messages, the quoted lines exceeded 5500 lines (I copied and pasted the message on KWrite), most of them empty. Needless to say, the exchanged text was nowhere near as long, more like a hundred lines at most.

Problem is, when I last replied to this message KMail started freezing. It would take up a whole core of the processor for about 30 seconds, and become totally unresponsive. Then, it would unfreeze for a few seconds and then start again. 

Also, selecting this message from the message list view causes KMail to freeze again, albeit for only a few seconds in that case (and it happens only once, the program then behaves normally).

In general, I think there is something iffy about the quoting process. Quoted messages tend to end up with considerable more lines than they originally contained. I will attach the last message so that you can verify that something is wrong with the quoting process.

Copying and pasting the (5000 line long) message in a new composer window seems to reproduce the behaviour.

I don't mind the message bloat so much, but the freezing is extremely annoying.

Using version 5.1.1 and openSUSE rpms. At your disposal for further testing.

Reproducible: Always

Steps to Reproduce:
1. Create a new message or reply to an old message with a large amount of quoted lines (not sure but more than 5000?)


Actual Results:  
Kmail freezes for 30 seconds every few seconds.

Expected Results:  
Kmail should behave normally