If you observe a delay in Office applications loading, it is often caused by the AntiVirus Software.
Fig.1: Excel stuck at loading stage
To solve this issue, three exceptions needs to be added in your AntiVirus configuration:
If UpSlide is still slow after adding theses 3 exceptions please contact us at firstname.lastname@example.org.
Note: this behavior is caused by VSTO inner workings (see https://blogs.msdn.microsoft.com/vsod/2008/10/31/office-customization-createsloads-dll-from-temporary-folder/ for details)