diff --git a/pageserver/src/tenant/blob_io.rs b/pageserver/src/tenant/blob_io.rs
index 78ecbcb9c1..52eafc72ee 100644
--- a/pageserver/src/tenant/blob_io.rs
+++ b/pageserver/src/tenant/blob_io.rs
@@ -74,6 +74,7 @@ where
         };
 
         dstbuf.clear();
+        dstbuf.reserve(len);
 
         // Read the payload
         let mut remain = len;
diff --git a/pageserver/src/tenant/delta_layer.rs b/pageserver/src/tenant/delta_layer.rs
index a908d66200..dcd6956640 100644
--- a/pageserver/src/tenant/delta_layer.rs
+++ b/pageserver/src/tenant/delta_layer.rs
@@ -260,8 +260,9 @@ impl Layer for DeltaLayer {
 
             // Ok, 'offsets' now contains the offsets of all the entries we need to read
             let mut cursor = file.block_cursor();
+            let mut buf = Vec::new();
             for (entry_lsn, pos) in offsets {
-                let buf = cursor.read_blob(pos).with_context(|| {
+                cursor.read_blob_into_buf(pos, &mut buf).with_context(|| {
                     format!(
                         "Failed to read blob from virtual file {}",
                         file.file.path.display()
diff --git a/pageserver/src/walredo.rs b/pageserver/src/walredo.rs
index 59dadbb1d3..f05bf46d96 100644
--- a/pageserver/src/walredo.rs
+++ b/pageserver/src/walredo.rs
@@ -740,7 +740,11 @@ impl PostgresRedoProcess {
         // This could be problematic if there are millions of records to replay,
         // but in practice the number of records is usually so small that it doesn't
         // matter, and it's better to keep this code simple.
-        let mut writebuf: Vec<u8> = Vec::new();
+        //
+        // Most requests start with a before-image with BLCKSZ bytes, followed by
+        // by some other WAL records. Start with a buffer that can hold that
+        // comfortably.
+        let mut writebuf: Vec<u8> = Vec::with_capacity((BLCKSZ as usize) * 3);
         build_begin_redo_for_block_msg(tag, &mut writebuf);
         if let Some(img) = base_img {
             build_push_page_msg(tag, &img, &mut writebuf);