Roger Meier's Forums

CoolTerm is the only serial port terminal I've used that isn't missing a vital feature and doesn't suck to use. In fact, I love it.

But then, after months of using it, it suddenly became slow and unresponsive. Sometimes I launch it and it's OK for a bit, except the COM port menu takes a second or so to react to clicks. After a few minutes everything starts to become nearly unusable. Every click takes seconds to respond. Even moving the window is unresponsive. Nothing else in Windows becomes slow.

Restarting the program doesn't help. Restarting my computer doesn't help. I suppose I could delete the program and redownload it, but given there doesn't appear to be any caching or files being saved, I haven't bothered.

Really, my question isn't if anyone has a solution. Rather, I just want to know if there is a cache in the home folder or in the registry that I haven't yet found that I can try deleting.

Still, I'll provide my specs:
Windows 11 Pro
13th Gen Intel(R) Core(TM) i5-13500HX 2.50 GHz
16 GB RAM

Does this happen after you have received a large amount of data? If so, I would recommend keeping the receive buffer size relatively small. 10-100kBytes.

Sorry I ignored the reply, I've been distracted.

I finally solved my issue.

I have a Serial Over Bluetooth link COM port. I believe I added it around the time the issue started. Disabling it makes CoolTerm respond like new again. I almost feel silly not trying something like that when I started having the issue, but I needed it for the task anyway.

Steps to recreate: Under Windows 11, add a Bluetooth COM port under Bluetooth & devices -> Devices -> More Bluetooth Settings -> COM Ports tab -> Add -> Outgoing.

When I have the device enabled, it takes a few seconds for the COM Port list in CoolTerm to appear when clicked, and over time the program becomes unresponsive, even if left in the background. After I disabled the device in Device Manager, I haven't had a slow down since.

Hopefully that helps if you choose to investigate.

Thanks for your post!

Yes, I have seen this issue (only on Windows) with some (very few) 'serial over bluetooth' devices. For some reason, when CoolTerm enumerates the available serial ports, the device driver takes a long time to respond, slowing the whole process down. CoolTerm automatically enumerates serial ports periodically (once per second) to detect changes to the available devices. Normally, this should be instantaneous, but if one of the devices pulls the break, then it will seem as if nothing is happening and CoolTerm is stalled.

There is a workaround in case you need to re-enable your serial/Bluetooth device:
- Hold the 'ALT' (or Option) key when selecting the 'Preferences...' menu item. This will enable an 'Advanced' tab in the preferences windows.
- In the 'Advanced' tab, select 'Skip automatic serial port enumeration'.

Not that this will skip all automatic enumeration, i.e. the 'Port' popup menu in the 'Options' will no longer automatically update when a device is disconnected or a new one is connect. You will need to press the 'Re-Scan serial port' button trigger a new enumeration automatically.

You may also be able to solve this issue with an updated device driver.

I hope this helps.

Roger