How much total RAM do you have installed? How much of the available RAM is in use after Quicken has started? Windows Task Manager will give you this information. 80% or higher?
Slow Performance issue for Laptop users:
Is your laptop plugged in while you're working with Quicken or are you running on battery with power saving reduced performance settings? Check your Control Panel / Power Options. Make sure the selected Power Plan allows for best performance while plugged in and while on battery.
Here's some more info to look at regarding performance: https://community.quicken.com/discussion/7915476/faq-are-there-any-windows-settings-that-can-improve-quicken-s-performance