Improve search performance by limiting the search scope

Find the last occurrence of the last character in the pattern and
perform the search algorithm only up to that point.

The effectiveness of this mechanism depends a lot on the shape of the
input and the pattern.

CHANGELOG.md

@@ -3,6 +3,45 @@ CHANGELOG
 
 0.50.0
 ------
+- Search performance optimization. You can observe 50%+ improvement in some scenarios.
+  ```sh
+  $ time wc < $DATA
+   5520118 26862362 897487793
+
+  real    0m1.320s
+  user    0m1.236s
+  sys     0m0.075s
+
+  $ time fzf --sync --bind load:abort < $DATA
+
+  real    0m0.479s
+  user    0m0.427s
+  sys     0m0.176s
+
+  $ hyperfine -w 1 -L bin fzf-0.49.0,fzf-7ce6452,fzf-a5447b8,fzf '{bin} --filter "///" < $DATA | head -30'
+
+  Benchmark 1: fzf-0.49.0 --filter "///" < $DATA | head -30
+    Time (mean ± σ):      2.002 s ±  0.024 s    [User: 14.447 s, System: 0.300 s]
+    Range (min … max):    1.964 s …  2.042 s    10 runs
+
+  Benchmark 2: fzf-7ce6452 --filter "///" < $DATA | head -30
+    Time (mean ± σ):      1.627 s ±  0.019 s    [User: 10.828 s, System: 0.271 s]
+    Range (min … max):    1.596 s …  1.651 s    10 runs
+
+  Benchmark 3: fzf-a5447b8 --filter "///" < $DATA | head -30
+    Time (mean ± σ):      1.524 s ±  0.025 s    [User: 9.818 s, System: 0.269 s]
+    Range (min … max):    1.478 s …  1.569 s    10 runs
+
+  Benchmark 4: fzf --filter "///" < $DATA | head -30
+    Time (mean ± σ):      1.318 s ±  0.025 s    [User: 8.005 s, System: 0.262 s]
+    Range (min … max):    1.282 s …  1.366 s    10 runs
+
+  Summary
+    fzf --filter "///" < $DATA | head -30 ran
+      1.16 ± 0.03 times faster than fzf-a5447b8 --filter "///" < $DATA | head -30
+      1.23 ± 0.03 times faster than fzf-7ce6452 --filter "///" < $DATA | head -30
+      1.52 ± 0.03 times faster than fzf-0.49.0 --filter "///" < $DATA | head -30
+  ```
 - Added `jump` and `jump-cancel` events that are triggered when leaving `jump` mode
   ```sh
   # Default behavior