JSFiddle - React, Tailwind, and code Playground

JavaScript

var str = "skf3awe;fouaffg[llchn33o[asjg[aoghjas[ofughapwtn4w[eogndf-gnq3o[4t[jscpsa";
for(var i=0; i<18; ++i){
    str+=str;
}
    
var t1 = new Date().getTime();
str.replace(/s/g,"@").replace(/a/g, "$");
document.write(new Date().getTime() - t1 + "<br/>");

var t2 = new Date().getTime();
str.replace(/a|s/g, function (m) { return m=='a' ? '@' : '$' });
document.write(new Date().getTime() - t2 + "<br/>");

var t3 = new Date().getTime();
str.replace(/[as]/g, function (m) { return m=='a' ? '@' : '$' });
document.write(new Date().getTime() - t3 + "<br/>");