This depends on multiple factors such as your network connection, your computer specifications, and the size of the project you're publishing. Please see our minimum requirements here.
To minimize lag or latency when uploading/publishing content to the device, we recommend connecting to the device over Ethernet.
If you are noticing lag/latency, we also recommend to make sure that you have published your project rather than viewing it in preview mode.
Lightform products were designed to use a publish model i.e. it is not designed primarily for viewing live visuals. Note that when you stream a preview of the project video, you are seeing a downsampled version that acts as a preview versus publishing the content actually uploads it to the device.
When publishing projects, all slides are rendered to 1080p (or the projector's resolution) with a bitrate of ~10Mb/s. For most content, this should result in no visual loss of quality.