Why is Android JSInterface so slow?

Question

I have a javascript calling a javascript interface many times (around 500 times sometimes), updating the page's UI from it. It sends a couple strings, and casts String result to string: ""+window.INTERFACENAME.function(...).

Without calling the function, it takes 43ms, but takes 6 or 7 seconds with the JSInterface call. Why is the JSInterface so slow?

Answer 1

My solution was to implement the same function in Javascript as the Java code. Messy, but it's much faster than calling Java. I suppose if it were required to make many calls to Java, it would be better to make one call with a list of inputs.