Try allocating more memory to PowerPoint.
Locate the PowerPoint icon, click it to select it (don't doubleclick to launch it).
Choose File, Get Info from the menu bar.
Choose Show: Memory
Increase the minimum amount by as much as you can.
Microsoft also recommends that Virtual Memory be turned ON.
From the Apple menu, choose Control Panels. Pick the Memory control panel.
Turn Virtual Memory ON
Restart the computer to defragment memory.
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