Why does Outlook slow down after I combine multiple PST files?

When you combine more than one PST file in Microsoft Outlook, the application can slow down since the new, larger PST file is harder to index and find. Outlook takes longer to open folders, search for emails, and sync data as the file size grows. Corruption risks and background indexing also impact performance. Use the Softaken Merge PST Tool to avoid these problems. It reliably merges PST files without slowing down Outlook or losing data.