What if:

```c
if (Z_STRVAL_P(header_name) == IS_STRING && Z_STRLEN_P(header_name) > sizeof("HTTP/x.y ")-1 && !memcmp(Z_STRVAL_P(header_name), "HTTP/", 5)) {
    phalcon_call_method_p1_noret(headers, "remove", header_name);
}
```

`memcmp` will be much faster than `phalcon_fast_strpos`