Most common cases related to application freezes are caused by your installed antivirus. If you have one, open it and access the Firewall and Scanner settings. There should be an Exclusions section from where you need to add Mozilla Thunderbird. The crash is caused by the search function and the protection modules available within your antivirus. Add the software to the exclusion list, and the antivirus won't interfere any more, therefore, you will have no more crashing and freezing issues.
Additionally, always update the application to the latest version. Go to Help > About to check for updates automatically.