diff --git a/src/inc/til/u8u16convert.h b/src/inc/til/u8u16convert.h
index b4d3cd9f8..af6e4f9b7 100644
--- a/src/inc/til/u8u16convert.h
+++ b/src/inc/til/u8u16convert.h
@@ -55,6 +55,14 @@ namespace til // Terminal Implementation Library. Also: "Today I Learned"
                 RETURN_HR_IF(E_ABORT, !base::CheckAdd(in.length(), _partialsLen).AssignIfValid(&capacity));
 
                 _buffer.clear();
+
+                // If we were previously called with a huge buffer we have an equally large _buffer.
+                // We shouldn't just keep this huge buffer around, if no one needs it anymore.
+                if (_buffer.capacity() > 16 * 1024 && (_buffer.capacity() >> 1) > capacity)
+                {
+                    _buffer.shrink_to_fit();
+                }
+
                 _buffer.reserve(capacity);
 
                 // copy UTF-8 code units that were remaining from the previous call (if any)
diff --git a/src/server/ApiMessage.cpp b/src/server/ApiMessage.cpp
index 598111c88..9287965d3 100644
--- a/src/server/ApiMessage.cpp
+++ b/src/server/ApiMessage.cpp
@@ -104,7 +104,14 @@ try
     {
         RETURN_HR_IF(E_FAIL, State.ReadOffset > Descriptor.InputSize);
 
-        ULONG const cbReadSize = Descriptor.InputSize - State.ReadOffset;
+        const ULONG cbReadSize = Descriptor.InputSize - State.ReadOffset;
+
+        // If we were previously called with a huge buffer we have an equally large _inputBuffer.
+        // We shouldn't just keep this huge buffer around, if no one needs it anymore.
+        if (_inputBuffer.capacity() > 16 * 1024 && (_inputBuffer.capacity() >> 1) > cbReadSize)
+        {
+            _inputBuffer.shrink_to_fit();
+        }
 
         _inputBuffer.resize(cbReadSize);
 
@@ -145,10 +152,17 @@ try
         ULONG cbWriteSize = Descriptor.OutputSize - State.WriteOffset;
         RETURN_IF_FAILED(ULongMult(cbWriteSize, cbFactor, &cbWriteSize));
 
+        // If we were previously called with a huge buffer we have an equally large _outputBuffer.
+        // We shouldn't just keep this huge buffer around, if no one needs it anymore.
+        if (_outputBuffer.capacity() > 16 * 1024 && (_outputBuffer.capacity() >> 1) > cbWriteSize)
+        {
+            _outputBuffer.shrink_to_fit();
+        }
+
         _outputBuffer.resize(cbWriteSize);
 
         // 0 it out.
-        std::fill(_outputBuffer.begin(), _outputBuffer.end(), (BYTE)0);
+        std::fill_n(_outputBuffer.data(), _outputBuffer.size(), BYTE(0));
 
         State.OutputBuffer = _outputBuffer.data();
         State.OutputBufferSize = cbWriteSize;