Ive got a late 2013 high-end (at the time) 15' macbook pro. Now it's on macOS sierra I use native resolution which mimics 1440*900 resolution but everything is just too big, I tried upscaled (1680*1050) about a day (with a 2560*1080 monitor hooked up) it looks fantastic and the size of the UIs are perfect for 15' display. But just after few hours the UI becomes lag (or no longer smooth), especially in Mission control, swiping between desktops and the exposé. I have to reboot the laptop to get the fluency back. I usually have chrome open with about 10 tabs, and PDF expert open with 50+ PDFs. Would you please tell me what causes this UI lags? is it because macos didn't do well about rendering the UI or just because my laptop (GT750M) is too old to deal with these *modern OS*? Just wondering if this is a common phenomenon so we can count on apple fixing this in the future or it means I need a new laptop. Thanks.