Currently display sparkline is default set to true and can be switched off indivdually for each device with an xAttribute option. If one would like to switch it off for all or most of the devices the config gets very lengthy with all these xAttribute statements. So it would be a good idea to set the default value of the attribute in settings part of the config too.
Set default values for xAttributes like displaySparkline in config.json
I request again for this feature. I decided to remove sparklines from nearly every device.
Meanwhile the config is growing very large and I am looking for any optimization to get it smaller.