php If / else函数可以导致CPU使用率增加吗？

I have let's say around 20,000 products on my website

And for every product and page to run this

if ($price == "0" ) {
  $text_price = "Call us ";
  $price = "for a price.";
  echo $text_price;
  echo $price;
}
else{
  echo $text_price;
  echo $price;
}

I have this code in around 5 different files for Product page, Manufacturer page, Category page and so on.

Could this get the CPU usage high in the sky? The site has around 800 sessions a day according to google analytics.

I wouldn't have thought it would have that much of an impact (800 a day isn't that much). Although I would write it like this.

if ($price == '0' ) {
  $text_price = 'Call us ';
  $price = 'for a price.';
}

echo $text_price;
echo $price;

there's no need to put the echo inside the if as it'll execute anyway afterwards. Single quotes mean that the string isn't parsed twice by the compiler.