I recommend (as you suggested) to either break them down into smaller batches, OR use the UI.Vision command line API, and move the CSV reading to e. g. a Powershell or Python script. To send values from the script to the macro use the “cmd_var1” switch:
cmd_var1=hello%21world, cmd_var2, cmd_var3 - Send values to a Kantu macro from the command line. Inside the macro you can access the value with the internal variables.