The problem
My wife was editing a PowerPoint document with a new template made by someone else and experienced slowness in editing. When typing, one had to wait the effect of action or every key press for seconds, because loaded had sudden 100% peaks. No, this was not about any sluggishness of the computer.
A quick search in the Google produced a list of problem candidates:
- Uncheck spelling check => Uncheck spelling as you type
- Incorrect printer driver => Too much trouble to try
- Enabled hardware graphics acceleration => No it was not enabled for Intel Graphics
- Shading and transparency on slide master => Looked prominent, no effect
- Potential incompatibility with Mac and Windows versions => Correct and compatible set of fints were used
- Graphics on slide master, put in a wrong way => How can you find these?
To save you from too much suspense, the last one was the actual culprit!
How you can avoid it?
Mitigation
In the Home tab, there is a Slide preview (thumbnails(/ Outline column on the left, which may as well be hidden behind the left edge. Take it visible and select Outline! because then no computing power is wasted drawing thumbnail pictures of every slide.
You may also choose to Hide background graphics in the Slide Master.
Best fix
But the above only mitigate the problem, they don’t remove it. In the case the above tricks helped, the root cause is likely to be bitmap graphics objects in the slide master. If you have taken a .jpg or .png picture and inserted it as a graphic object in the Slide Master or any of the Slide Layouts, that was a wrong thing to do. Instead, you should use Format background > Picture or texture fill > From file.. . Then select the picture file to insert as the slide master background and adjust the stretch settings as necessary. You’ll want to press “Apply to all” to set the background of all slides.
This way the background doesn’t charge load to thumbnail view. In the case you want to set a different background to individual slide, you can insert the graphic object to the slide and send it back of other objects.
Why did it happen?
My theory is that the slide thumbnails are generated in a such way, that first the slide master base is rendered once to thumbnail and used in all. Then the additional objects in the slide master and the slide are rendered individually for each slide. Rendering a miniature version of a bitmap of size of a full slide is a quite heavy operation, and the operation will be executed for each and every slide.
Is it a bug?
I consider this as an unconvenient feature, not really a bug. Everybody should educate themselves how to use tools correctly, not just use them.