(perf) Cache scrollItemsLength

1 files changed, 8 insertions, 2 deletions

diff --git a/ui/form/ListScrollForm.js b/ui/form/ListScrollForm.js
index 300fed4..3f16416 100644
--- a/ui/form/ListScrollForm.js
+++ b/ui/form/ListScrollForm.js
@@ -62,6 +62,8 @@ module.exports = class ListScrollForm extends Form {
         item.visible = false
       }
     }
+
+    delete this._scrollItemsLength
   }
 
   keyPressed(keyBuf) {
@@ -151,8 +153,12 @@ module.exports = class ListScrollForm extends Form {
   }
 
   getScrollItemsLength() {
-    const lastInput = this.inputs[this.inputs.length - 1]
-    return this.getScrollPositionOfElementAtEndOfView(lastInput)
+    if (typeof this._scrollItemsLength === 'undefined') {
+      const lastInput = this.inputs[this.inputs.length - 1]
+      this._scrollItemsLength = this.getScrollPositionOfElementAtEndOfView(lastInput)
+    }
+
+    return this._scrollItemsLength
   }
 
   getItemPos(item) {