Oh by "more complex" operations I referred to multiple cursors and multi line regex searches. I've noticed some performance problems in my own editor but it's mostly because "lines" become fragmented, if you allocate all the lines with their own allocation, they might be far away from each other in memory. It's especially true when programming where lines are relatively short.
Regex searches and code highlight might introduce some hitches due to all of the seeking.
Regex searches and code highlight might introduce some hitches due to all of the seeking.