<style>
    .noligatures { text-rendering: optimizeSpeed; }
    .ligatures { text-rendering: optimizeLegibility; }
</style>
<body style="font-size: 36px;">
    <div class="noligatures">file</div>
    <div class="ligatures">file</div>
    <div class="ligatures">file</div>
    <div class="noligatures">file</div>
    <div class="ligatures">file</div>
    <div class="ligatures">file</div>
</body>