针对不同博客，改动略有不同，本文仅供参考，我这里把fps开关放到了中控台

效果预览

魔改步骤

1. 修改 themes/butterfly/layout/includes/header/nav.pug

   #page-name-mask
   #page-name
   a#page-name-text(onclick= 'btf.scrollToDest(0,500)')=navTitleName
   #menus
   !=partial('includes/header/menu_item', {}, {cache: true})
   +  #nav-left
   +    #fps-group
   +      #fps
   +      span.fpsText=_p('FPS')

2. 修改 themes/butterfly/layout/includes/console.pug

   if theme.console.keyboard.enable
   .console-btn-item#consoleKeyboard(onclick='manxin.keyboardToggle()', title='快捷键开关')
      a.keyboard-switch
          i.fas.fa-keyboard
   .console-btn-item#consoleCommentBarrage(onclick='manxin.switchCommentBarrage()', title='热评开关')
      a.commentBarrage
          i.fa-solid.fa-message
   +   .console-btn-item#consoleFPS(onclick='manxin.FPSToggle()', title='帧率显示开关')
   +       a.FPS-switch
   +           i.fas.fa-gauge

3. 新建 themes/butterfly/source/manxin/fps.js（引入js略）

   let Jay_showFPS = !1;
   "true" === localStorage.getItem("showFPS") ?
   ((Jay_showFPS = !0),
       document.querySelector("#fps-group").classList.add("show"),
       document.querySelector("#consoleFPS").classList.add("on")) :
   ((Jay_showFPS = !1),
       document.querySelector("#fps-group").classList.remove("show"),
       document.querySelector("#consoleFPS").classList.remove("on"));
   var showFPS = (function() {
   let e,
       t,
       o,
       n,
       a,
       i =
       window.requestAnimationFrame ||
       window.webkitRequestAnimationFrame ||
       window.mozRequestAnimationFrame ||
       window.oRequestAnimationFrame ||
       window.msRequestAnimationFrame ||
       function(e) {
           window.setTimeout(e, 1e3 / 60);
       };
   (e = 0),
   (t = Date.now()),
   (n = function() {
       (o = Date.now() - t),
       (e += 1),
       o >= 1e3 && ((t += o), a(e), (e = 0)),
           i(n);
   }),
   (a = function(e) {
       $("#fps").html(e);
   }),
   n();
   })();
   var manxin = {
   FPSToggle: function() {
       Jay_showFPS
           ?
           ((Jay_showFPS = !1),
               document.querySelector("#fps-group").classList.remove("show"),
               document.querySelector("#consoleFPS").classList.remove("on"),
               localStorage.setItem("showFPS", "false")) :
           ((Jay_showFPS = !0),
               document.querySelector("#fps-group").classList.add("show"),
               document.querySelector("#consoleFPS").classList.add("on"),
               localStorage.setItem("showFPS", "true"));
   },
   };

4. 新建 themes/butterfly/source/manxin/fps.css（引入css略）

   #fps-group.show {
   opacity: 1;
   }
   .nav-fixed #fps-group,
   .not-top-img #fps-group {
   color: var(--Jay-fontcolor);
   }
   #fps-group {
   opacity: 0;
   display: flex;
   flex-direction: column;
   margin-left: 16px;
   color: var(--Jay-white);
   }
   #fps {
   z-index: 10000;
   font-size: 12px;
   font-weight: 700;
   transition: all 0.3s ease 0s;
   line-height: 1;
   }
   #fps-group .fpsText {
   font-size: 12px;
   line-height: 1;
   opacity: 0.6;
   }