Don't zero memory when we don't have to. (#578)
diff --git a/src/OpenSSL/_util.py b/src/OpenSSL/_util.py
index 48bcbf5..cf8b888 100644
--- a/src/OpenSSL/_util.py
+++ b/src/OpenSSL/_util.py
@@ -12,6 +12,12 @@
lib = binding.lib
+# This is a special CFFI allocator that does not bother to zero its memory
+# after allocation. This has vastly better performance on large allocations and
+# so should be used whenever we don't need the memory zeroed out.
+no_zero_allocator = ffi.new_allocator(should_clear_after_alloc=False)
+
+
def text(charp):
"""
Get a native string type representing of the given CFFI ``char*`` object.