However, as you continue using MS Outlook over the years, your mailbox data accumulates and can cause performance issues. This happens because your PST File has become large in size. If you have ever faced slow loading, lag, or even corruption issues in Outlook, it is likely due to an oversized PST File. That is where a PST File split tool comes in handy. https://www.vsoftware.org/blog/why-you-need-a-pst-split-tool-for-your-outlook-emails.html