Hi there I wonder if anyone can help me with my problem. I am building an Programming Editor for my Healthcare Software at work. The editor that comes with it is useless. One formular i am using notepad to programme has over 20,000 lines of codes. I have started making an editor and the problem is it takes ages to read all the keywords and find the line and add this to a Treeview control. I use Regular Expression to reduce the time to find the keywords. However, i have to loop over each item in the Regular Expression Match Collections in order to find the line where each match occurs. This will enable me to add each keywords and the line number to the tree view control. This loop with my 20,000 lines of codes seems to take ages. Can someone tell me how can i increase the performance? Shall i use Multithreading to do all the looping in the background? However, this will only hide the problems. When the Form appears and the user clicks the treeview structure, the background tasks may not have been completed yet. Can anyone tells me how to solve this performance problem?