Probably. Memory usage will depend mostly on the number of open tabs (or windows) and the size of the scrollback in each.
The storage of history in Konsole is not space efficient and there is a lot that could be done to improve it. Currently it uses 11 bytes per non-blank character (2 for the character itself + 9 for formatting) + (at least) 17 bytes per line. However, given the default settings of a maximum of 1000 lines, with a relatively small average length and normal usage habits of 4-10 tabs open means that memory usage does not grow huge.
One important thing to note is that no music player or web browser is open which makes the picture look quite different from that most users would see - with Firefox being the dominating application by an order of magnitude.
The standard top utility, as is well known, does not give very useful figures. Modern versions of KDE's System Monitor are much better in my view.