diff --git a/doc/source/whatsnew/v2.1.0.rst b/doc/source/whatsnew/v2.1.0.rst
index 0772cadf6e737..e860d59f2e5bd 100644
--- a/doc/source/whatsnew/v2.1.0.rst
+++ b/doc/source/whatsnew/v2.1.0.rst
@@ -88,6 +88,7 @@ Other enhancements
 - Improve error message when setting :class:`DataFrame` with wrong number of columns through :meth:`DataFrame.isetitem` (:issue:`51701`)
 - Improved error message when creating a DataFrame with empty data (0 rows), no index and an incorrect number of columns. (:issue:`52084`)
 - Let :meth:`DataFrame.to_feather` accept a non-default :class:`Index` and non-string column names (:issue:`51787`)
+- Performance improvement in :func:`read_csv` (:issue:`52632`) with ``engine="c"``
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/_libs/src/parser/tokenizer.c b/pandas/_libs/src/parser/tokenizer.c
index fed9b26d479cb..e60fc6bf75f91 100644
--- a/pandas/_libs/src/parser/tokenizer.c
+++ b/pandas/_libs/src/parser/tokenizer.c
@@ -664,9 +664,7 @@ static int parser_buffer_bytes(parser_t *self, size_t nbytes,
     ((!self->delim_whitespace && c == ' ' && self->skipinitialspace))
 
 // applied when in a field
-#define IS_DELIMITER(c)                                   \
-    ((!self->delim_whitespace && c == self->delimiter) || \
-     (self->delim_whitespace && isblank(c)))
+#define IS_DELIMITER(c) ((c == delimiter) || (delim_whitespace && isblank(c)))
 
 #define _TOKEN_CLEANUP()                                                \
     self->stream_len = slen;                                            \
@@ -721,6 +719,9 @@ int tokenize_bytes(parser_t *self,
     const char lineterminator = (self->lineterminator == '\0') ?
             '\n' : self->lineterminator;
 
+    const int delim_whitespace = self->delim_whitespace;
+    const char delimiter = self->delimiter;
+
     // 1000 is something that couldn't fit in "char"
     // thus comparing a char to it would always be "false"
     const int carriage_symbol = (self->lineterminator == '\0') ? '\r' : 1000;