Client lag, DM has none

I am having issues with a map I have in roll20. The players will experience extreme lag when using it (various pc types, various browsers) but I have no issues with it. The map isn't small but not huge either. I do utilize line of site/dynamic lighting and "enforce LOS". Is there anything I can poke around to find the cause of this?

Please send me a join link and I will come take a look. Also, please have those players experiencing the lag post so we can troubleshoot with them directly.

I'm one of the players seeing severe lag.

Some of the lag problem could be where their ISP is at or what they internet connection is. If they are using satellite connection, they will experience lag (which is influenced by the weather), if they are over in an European area their lag could range from minor to severe depending on the conditions of their lines, quality of their service, and other incidences which include hackers doing a DOS event on a server where they connection has to bounce through. There are many factors that could cause lag that do not involve roll20 and the player's actual browser. I hope you get it resolved and good luck.

The problem was determined to be the use of freehand on the Dynamic Lighting layer. Celestian is aware of this now and should be using polygon/line on the DL layer in the future.

Yup, I'll try and test it out next game (9/19 I think). Thanks for your help Gauss!