function                                             old     new   delta
unpack_lzma_stream                                  2482    2400     -82
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-82)             Total: -82 bytes
$ grep LZMA_FAST .config
CONFIG_FEATURE_LZMA_FAST=y
$ ./busybox_old  unlzma  < ../linux-2.6.23.tar.lzma > /dev/null
Using fallback suid method

real	0m10.957s
user	0m10.901s
sys	0m0.044s
$ ./busybox_unstripped unlzma  < ../linux-2.6.23.tar.lzma  > /dev/null
Using fallback suid method

real	0m10.781s
user	0m10.713s
sys	0m0.056s

--- archival/libunarchive/decompress_unlzma.c	2007-09-03 13:48:34.000000000 +0200
+++ archival/libunarchive/decompress_unlzma.c	2008-03-03 10:51:46.000000000 +0100
@@ -317,8 +317,15 @@
 				prob_lit = prob + mi;
 				rc_get_bit(rc, prob_lit, &mi);
 			}
-			previous_byte = (uint8_t) mi;
 
+			state -= 3;
+			if (state < 4-3)
+				state = 0;
+			if (state >= 10-3)
+				state -= 6-3;
+
+			previous_byte = (uint8_t) mi;
+ one_byte:
 			buffer[buffer_pos++] = previous_byte;
 			if (buffer_pos == header.dict_size) {
 				buffer_pos = 0;
@@ -327,12 +334,6 @@
 					goto bad;
 				USE_DESKTOP(total_written += header.dict_size;)
 			}
-			if (state < 4)
-				state = 0;
-			else if (state < 10)
-				state -= 3;
-			else
-				state -= 6;
 		} else {
 			int offset;
 			uint16_t *prob_len;
@@ -361,15 +362,7 @@
 						while (pos >= header.dict_size)
 							pos += header.dict_size;
 						previous_byte = buffer[pos];
-						buffer[buffer_pos++] = previous_byte;
-						if (buffer_pos == header.dict_size) {
-							buffer_pos = 0;
-							global_pos += header.dict_size;
-							if (full_write(dst_fd, buffer, header.dict_size) != header.dict_size)
-								goto bad;
-							USE_DESKTOP(total_written += header.dict_size;)
-						}
-						continue;
+						goto one_byte;
 					} else {
 						rc_update_bit_1(rc, prob);
 					}