update readme

diff --git a/readme.md b/readme.md
index 8b07f9a..0bd2a94 100644
--- a/readme.md
+++ b/readme.md

@@ -578,7 +578,8 @@
   (if possible), and mimalloc aborts on corrupted meta data detection.
 - Large blocks (> 512 KiB) are followed by a guard page.
 
-With `CHECKED` (the default with `-DMI_MTE` and `-DMI_PAC`), the performance impact is still small (usually less than 10%, but can be 2x slower):
+With `CHECKED` (the default with `-DMI_MTE` and `-DMI_PAC`), the performance and memory impact
+is still relatively small (usually less than 10%, but can be 2x slower):
 
 - All free list pointers are
   [encoded](include/mimalloc/alloc/page.h#L582)
@@ -591,7 +592,7 @@
 - Reuse of freed blocks is delayed (until 1/8th of a page is free) and a random number of the most recently
   freed blocks is held back, making it harder to reclaim a just-freed block (to exploit use-after-free).
 
-With `ON`, performance and memory usage is impacted a bit more (usually less than 25%, but can be 2x slower):
+With `ON`, performance and memory usage is impacted a bit more (usually less than 25%, but can be 2 to 3x slower):
 
 - Padding (8 bytes) is added at the end of each heap block to detect heap block overflows (detected once the block is freed),
 and double free's.