--- /dev/null
+Reduce the initial buffer size for open_memstream (used by vasprintf),
+as most strings are usually smaller than that.
+Realloc the buffer after finishing the string to further reduce size.
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+
+--- a/libc/stdio/vasprintf.c
++++ b/libc/stdio/vasprintf.c
+@@ -39,6 +39,8 @@ int vasprintf(char **__restrict buf, con
+ if (rv < 0) {
+ free(*buf);
+ *buf = NULL;
++ } else {
++ *buf = realloc(*buf, rv + 1);
+ }
+ }
+
+--- a/libc/stdio/open_memstream.c
++++ b/libc/stdio/open_memstream.c
+@@ -17,6 +17,8 @@
+
+ #define COOKIE ((__oms_cookie *) cookie)
+
++#define MEMSTREAM_BUFSIZ 256
++
+ typedef struct {
+ char *buf;
+ size_t len;
+@@ -134,7 +136,7 @@ FILE *open_memstream(char **__restrict b
+ register FILE *fp;
+
+ if ((cookie = malloc(sizeof(__oms_cookie))) != NULL) {
+- if ((cookie->buf = malloc(cookie->len = BUFSIZ)) == NULL) {
++ if ((cookie->buf = malloc(cookie->len = MEMSTREAM_BUFSIZ)) == NULL) {
+ goto EXIT_cookie;
+ }
+ *cookie->buf = 0; /* Set nul terminator for buffer. */