lib/PublicInbox/View.pm     | 14 ++++++--------
 lib/PublicInbox/ViewDiff.pm | 45 +++++++++++++++++++++------------------------

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 2f99179e969f99e891e4139ddeb5561375fe4ee8..3dbf8bac33f8c9ecc6eb3e19fb5b406f718aaf7a 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -560,7 +560,7 @@ 	# $p - from each_part: [ Email::MIME-like, depth, $idx ]
 	my ($part, $depth, $idx) = @$p;
 	my $ct = $part->content_type || 'text/plain';
 	my $fn = $part->filename;
-	my $rv = $ctx->{obuf};
+	my $rv = $ctx->{obuf} //= \(my $obuf = '');
 	my ($s, $err) = msg_part_text($part, $ct);
 	$s // return $$rv .= (attach_link($ctx, $ct, $p, $fn) // '');
 	if ($part->{is_submsg}) {
@@ -618,18 +618,16 @@ 		$$rv .= attach_link($ctx, $ct, $p, $fn, $err);
 		$$rv .= "\n";
 	}
 	delete $part->{bdy}; # save memory
-	foreach my $cur (@sections) {
+	for my $cur (@sections) { # $cur may be huge
 		if ($cur =~ /\A>/) {
 			# we use a <span> here to allow users to specify
 			# their own color for quoted text
-			$$rv .= qq(<span\nclass="q">);
-			$$rv .= $l->to_html($cur);
-			$$rv .= '</span>';
+			$ctx->zmore(qq(<span\nclass="q">),
+					$l->to_html($cur), '</span>');
 		} elsif ($diff) {
 			flush_diff($ctx, \$cur);
-		} else {
-			# regular lines, OK
-			$$rv .= $l->to_html($cur);
+		} else { # regular lines, OK
+			$ctx->zmore($l->to_html($cur));
 		}
 		undef $cur; # free memory
 	}
diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index 076aa1af6546c15fc209bc3cfcf0cf7cd826c3eb..36601910ad1ef9d5518109722c4b91ddfaa31536 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -156,10 +156,7 @@ 	} else {
 		warn "BUG? <$$x> had no ^index line";
 	}
 	$$x =~ s!^diff --git!anchor1($ctx, $pb) // 'diff --git'!ems;
-	my $dst = $ctx->{obuf};
-	$$dst .= qq(<span\nclass="head">);
-	$$dst .= $$x;
-	$$dst .= '</span>';
+	$ctx->zmore(qq(<span\nclass="head">$$x</span>));
 	$dctx;
 }
 
@@ -182,9 +179,10 @@ 		$$x .= pop @x; # $3 /^ \d+ files? /
 		my $ch = $ctx->{changed_href} // '#related';
 		$$x .= qq(<a href="$ch">changed</a>,);
 		$$x .= ascii_html(pop @x); # $4: insertions/deletions
-		$$x .= $lnk->to_html(pop @x); # notes, commit message, etc
+		# notes, commit message, etc
+		$ctx->zmore($$x .= $lnk->to_html(pop @x));
 	} else {
-		$ctx->{-linkify}->to_html($$x);
+		$ctx->zmore($ctx->{-linkify}->to_html($$x));
 	}
 }
 
@@ -195,8 +193,7 @@
 	my @top = split($EXTRACT_DIFFS, $$cur);
 	undef $$cur; # free memory
 
-	my $linkify = $ctx->{-linkify};
-	my $dst = $ctx->{obuf};
+	my $lnk = $ctx->{-linkify};
 	my $dctx; # {}, keys: Q, oid_a, oid_b
 
 	while (defined(my $x = shift @top)) {
@@ -223,28 +220,28 @@ 					(?:^@@ [^\n]+\n))/xsm, $x)) {
 				if (!defined($dctx)) {
 					$after .= $s;
 				} elsif ($s =~ s/\A@@ (\S+) (\S+) @@//) {
-					$$dst .= qq(<span\nclass="hunk">);
-					$$dst .= diff_hunk($dctx, $1, $2);
-					$$dst .= $linkify->to_html($s);
-					$$dst .= '</span>';
-				} elsif ($s =~ /\A\+/) {
-					$$dst .= qq(<span\nclass="add">);
-					$$dst .= $linkify->to_html($s);
-					$$dst .= '</span>';
+					$ctx->zmore(qq(<span\nclass="hunk">) .
+						diff_hunk($dctx, $1, $2) .
+						$lnk->to_html($s) .
+						'</span>');
+				} elsif ($s =~ /\A\+/) { # $s may be huge
+					$ctx->zmore(qq(<span\nclass="add">),
+							$lnk->to_html($s),
+							'</span>');
 				} elsif ($s =~ /\A-- $/sm) { # email sig starts
 					$dctx = undef;
 					$after .= $s;
-				} elsif ($s =~ /\A-/) {
-					$$dst .= qq(<span\nclass="del">);
-					$$dst .= $linkify->to_html($s);
-					$$dst .= '</span>';
-				} else {
-					$$dst .= $linkify->to_html($s);
+				} elsif ($s =~ /\A-/) { # $s may be huge
+					$ctx->zmore(qq(<span\nclass="del">),
+						$lnk->to_html($s),
+						'</span>');
+				} else { # $s may be huge
+					$ctx->zmore($lnk->to_html($s));
 				}
 			}
-			$$dst .= diff_before_or_after($ctx, \$after) if !$dctx;
+			diff_before_or_after($ctx, \$after) if !$dctx;
 		} else {
-			$$dst .= diff_before_or_after($ctx, \$x);
+			diff_before_or_after($ctx, \$x);
 		}
 	}
 }