They are basically free when you have this little data. 1k cells updates 10 times a second means that you have around 100 micro seconds per cell, you can do thousands of lookups in that time. The only things which could even come close to costing 100 micro seconds are if you accidentally re-flow the html each cell update, re-render the html each cell update, send a http request each cell update or if you go through all the data each cell or the framework you are using is extremely inefficient or other unnecessary work. Each of those are easily fixable by doing the html and javascript by hand instead of using frameworks.