Run a speed test and compare it to Zoom's bandwidth requirements. Your upload bandwidth should be at least 1.8mbps for 1080p video and screen sharing. You may need to upgrade your service with your Internet Service Provider.
Minimize other uses of bandwidth in your household by limiting nonessential internet use while you are using Zoom, such as gaming, music and video streaming.
Are you wired or wireless?
Wired connections tend to be better than wireless connections.
Try connecting your computer directly to your router via a wired Ethernet cable instead of relying on the WiFi in your home (newer laptops may need an adapter).
WiFi connections tend to be better than cellular (3G/4G/LTE) connections.
If you are connected wirelessly, try moving your laptop closer to your wireless access point or router. The fewer walls between you and your router, the better your signal will be.
Make sure your WiFi network is password protected, to prevent unwanted usage.
If your home WiFi offers a choice of connecting at 5GHz or 2.4 GHz, connect to the 5GHz band.
Computer Hardware/Operating System
Does your machine meet Zoom's system requirements?
If you're using the Zoom web client, is your browser up to date? (Check something like WhatIsMyBrowser.com to check if your browser is up to date and get instructions to upgrade, if needed.)
Mute yourself when you're not speaking.
When your microphone is on, Zoom will devote part of your Internet connection to an audio stream for you, even if you are not speaking. Mute your microphone when you do not need it, and you will allow Zoom to use your Internet connection more effectively.
Uncheck "Enable HD" - Sending high definition (HD) webcam video requires more bandwidth than sending non-HD. Disabling HD video will free up more of your Internet connection for other parts of your Zoom meeting.
Turn off your virtual background.
When not presenting, mute your video feed to conserve upload bandwidth.
Are you running anything else on your computer (or any other computers and devices that share your Internet connection) that's using lots of bandwidth? Such as:
Large downloads or large uploads
Streaming video (e.g. Netflix, Hulu, YouTube, etc.)
Cloud backups or cloud file synchronizations (e.g. OneDrive, Dropbox)
Zoom meetings can demand significant memory and processing power from your computer. Closing other applications, ones you do not need during the session, will help Zoom run better.
If you are going to share your screen, and you encounter performance issues during screen sharing, here are some things to help:
Share a non-maximized application rather than your whole screen. Sharing a smaller portion of your screen in this way will reduce upload bandwidth requirements.
Where is the file that you're sharing? If the file is stored online, on the T drive, or in a Cloud-based service like OneDrive, you might have a slower/less quality experience than if the file is located on your local machine. You may need to move the files you will use to your local machine.