I've got a large JS program which qjs takes ~1.5 seconds just to parse/load. If I profile the evaluation using gprof, then it shows that over a third of the time is spent in find_var alone:

Flat profile:

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls   s/call   s/call  name    
 36.65      1.84     1.84   275818     0.00     0.00  find_var
 12.75      2.48     0.64   212052     0.00     0.00  JS_CallInternal
 11.55      3.06     0.58   100362     0.00     0.00  get_var_ref
...

Given that every timefind_var is called it iterates through all variables in the scope until finding the target variable, it looks like this is causing a lot of repeated iteration over the same variables when fd->var_count is large (15951 in my case):

static int find_var(JSContext *ctx, JSFunctionDef *fd, JSAtom name)
{
    int i;
    for(i = fd->var_count; i-- > 0;) {
        if (fd->vars[i].var_name == name && fd->vars[i].scope_level == 0)
            return i;
    }
    return find_arg(ctx, fd, name);
}

Could this be replaced with a lookup/hashtable or similar in the JSFunctionDef object? Or is there a simpler alternative?