After 3hour chat w/ IB Support this morning: => IF you have issues w/ unusually slow TWS load, it may be due to an issue that is suspected to be related to chart processing in v979 => WORKAROUND: install v978 Worked for me, at least. Since ~Jun loads have been periodically extremely slow (slower than usual) as much as 30mins, and sometimes never completed, succeeding only after Mac restart (not sure that was the fix, btw). A possible symptom of the issue is TWS periodically unable to process charts that have multiple panes, where 2+ of the panes have annotations on the same tradable. TWS popups sometimes report these charts as having syntax errors, and TWS tends to strip off the annotations in order to load them. Yet same charts are loadable from disk, and the annotations survive manual file load. One more reason to always back up TWS charts to local disk. My env: Mac OS Catalina, 12GB+ mem, max TWS mem allocated P.S: too bad IB does not itself provide this kind of alert -- def ? Of course I may be mistaken if it does ...