App size of 5+ MB, may I ask if it is inferior to 20MB? If so, that could mean you did not used crosswalk, which implies bad performances on android versions up to 5, due to the poor webview of those.
Can you try the web version you posted in either chrome or firefox for android?
hundredfold I would guess from his event sheet (if it is the only one), that there is no optimisation to do on his code, as the majority of the performances problem would be elsewhere (if you have performances issues with so little things happenning, unless you are using physics, you can bet the interpretor is most likely unable to do the job, and there does not seems to be an obvious performance swallowing event, then the apk size tells me that crosswalk was not the one being used).