I am the dev of the plugin. Thanks for the info, I will try to address that. Notice that the performance is much better when you turn off row/col headers.
rowHeaders: false,
colHeaders: false,
That is the newest feature and I am sure it can be optimised.
It would be the best if you could help me with the plugin by issueing a ticket in GitHub. I do this for my own startup (www.giraffeapp.com) and I have to split time between this and other tasks.