Small performance improvements to checking for chars in paths (#1143)

CHANGES/1143.misc.rst

@@ -0,0 +1 @@
+Improved performance of processing paths -- by :user:`bdraco`.

yarl/_url.py

@@ -789,7 +789,7 @@ def raw_parts(self) -> Tuple[str, ...]:
             else:
                 parts = ["/"] + path[1:].split("/")
         else:
-            if path.startswith("/"):
+            if path and path[0] == "/":
                 parts = ["/"] + path[1:].split("/")
             else:
                 parts = path.split("/")
@@ -868,7 +868,7 @@ def _validate_authority_uri_abs_path(host: str, path: str) -> None:
 
         Raise ValueError if not.
         """
-        if host and path and not path.startswith("/"):
+        if host and path and not path[0] == "/":
             raise ValueError(
                 "Path in a URL with authority should start with a slash ('/') if set"
             )
@@ -1395,7 +1395,7 @@ def with_suffix(self, suffix: str) -> "URL":
         """
         if not isinstance(suffix, str):
             raise TypeError("Invalid suffix type")
-        if suffix and not suffix.startswith(".") or suffix == ".":
+        if suffix and not suffix[0] == "." or suffix == ".":
             raise ValueError(f"Invalid suffix {suffix!r}")
         name = self.raw_name
         if not name: