Another option would be to export the layer with the join to a .shp file. I have noticed quite a bit of lag time working with joined data in ArcGIS.
I'd go with that too. If you export your data with a joined .csv file, the attribute of the .csv will be in the output shapefile. Should be easier and faster then.
It's not suppose to froze with "only" a couple hundred thousand features. I did it with millions. It was slow (5-10 minutes?) but it worked.
Creating an index would be a good idea too.
I tried this and that's what took forever. I joined the CSV to the SHP and the data shows up fine, I can scroll through the million+ attribute table with no problem but when I try to either select a subset of the table based on attributes or just try to export to a new SHP it takes forever. Last night before leaving work I ran a select by attributes, set the ArcMap.exe process in my task manager to realtime priority and left for the evening. This morning ArcMap was still just sitting there doing nothing.
I probably should mention I have ArcView 9.2 so the JoinField option isn't available to me.