Toad is slow when using the schema browser.
On the same machine other applications seem to work fine.
Please select only the tabs you need in the Schema Browser by doing the following:
1. Right-click on any of the schema tabs or objects from the drop-down list and click on 'Configure'.
2. On the 'Configure Browser Tabs' window, uncheck any unneeded tabs under the 'Visible' column.
3. Click OK and re-test the issue.