Avoided isinstance(…, Variable) calls in FilterExpression.resolve().

By determining the variable type within __init__() instead of resolve() 
we can skip an isinstance() check at template runtime. Templates are
executed in production more often than the parse trees themselves,
assuming the cached Loader is used.

1 files changed, 2 insertions, 1 deletions

diff --git a/django/template/base.py b/django/template/base.py
index 0dec9940ab..078be8b383 100644
--- a/django/template/base.py
+++ b/django/template/base.py
@@ -694,9 +694,10 @@ class FilterExpression:
 
         self.filters = filters
         self.var = var_obj
+        self.is_var = isinstance(var_obj, Variable)
 
     def resolve(self, context, ignore_failures=False):
-        if isinstance(self.var, Variable):
+        if self.is_var:
             try:
                 obj = self.var.resolve(context)
             except VariableDoesNotExist: