Thunderbird 68.7.0 Windows 10 Pro, 16Gb Ram, Intel 3.1Ghz, Microsoft Defender and MalwareBytes This problem just started within the last 30 days. When composing emails, at times Thunderbird will freeze, stop displaying my letters typed and when it returns to operation, it's like slow motion. One letter at a time appears at the rate of about 1 per second, or 5 seconds for a 5 letter word. I keep my folders compacted and only very important emails are stored over 90 days.